Revert "removing lowres support"

There have been multiple user complaints about loosing this feature
while its not clear the 3% speedloss claims where real or fabricated.
My own testing indicates no statistically significant speed difference
both with mpeg2 and mpeg4, and if at all the code with lowres support
is a tiny bit faster than without.

This reverts commit 92ef4be4, reversing
changes made to 2e07f429.

Conflicts:

	cmdutils.c
	libavcodec/arm/vp8dsp_init_arm.c
	libavcodec/mpegvideo.c
	libavcodec/mpegvideo.h
	libavutil/arm/Makefile
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/flvdec.c

@@ -127,6 +127,7 @@ AVCodec ff_flv_decoder = {
     .close          = ff_h263_decode_end,
     .decode         = ff_h263_decode_frame,
     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("Flash Video (FLV) / Sorenson Spark / Sorenson H.263"),
     .pix_fmts       = ff_pixfmt_list_420,
 };

libavcodec/h261dec.c

@@ -658,5 +658,6 @@ AVCodec ff_h261_decoder = {
     .close          = h261_decode_end,
     .decode         = h261_decode_frame,
     .capabilities   = CODEC_CAP_DR1,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("H.261"),
 };

libavcodec/h263dec.c

@@ -151,7 +151,7 @@ static int get_consumed_bytes(MpegEncContext *s, int buf_size){
 
 static int decode_slice(MpegEncContext *s){
     const int part_mask= s->partitioned_frame ? (ER_AC_END|ER_AC_ERROR) : 0x7F;
-    const int mb_size = 16;
+    const int mb_size= 16>>s->avctx->lowres;
     s->last_resync_gb= s->gb;
     s->first_slice_line= 1;
 
@@ -766,6 +766,7 @@ AVCodec ff_h263_decoder = {
     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 |
                       CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
     .flush          = ff_mpeg_flush,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
     .pix_fmts       = ff_hwaccel_pixfmt_list_420,
 };

libavcodec/intrax8.c

@@ -716,6 +716,7 @@ av_cold void ff_intrax8_common_end(IntraX8Context * w)
  * The parent codec must call MPV_frame_start(), ff_er_frame_start() before calling this function.
  * The parent codec must call ff_er_frame_end(), MPV_frame_end() after calling this function.
  * This function does not use MPV_decode_mb().
+ * lowres decoding is theoretically impossible.
  * @param w pointer to IntraX8Context
  * @param dquant doubled quantizer, it would be odd in case of VC-1 halfpq==1.
  * @param quant_offset offset away from zero

libavcodec/mjpegdec.c

@@ -940,6 +940,21 @@ static int ljpeg_decode_yuv_scan(MJpegDecodeContext *s, int predictor,
     return 0;
 }
 
+static av_always_inline void mjpeg_copy_block(uint8_t *dst, const uint8_t *src,
+                                              int linesize, int lowres)
+{
+    switch (lowres) {
+    case 0: copy_block8(dst, src, linesize, linesize, 8);
+        break;
+    case 1: copy_block4(dst, src, linesize, linesize, 4);
+        break;
+    case 2: copy_block2(dst, src, linesize, linesize, 2);
+        break;
+    case 3: *dst = *src;
+        break;
+    }
+}
+
 static int mjpeg_decode_scan(MJpegDecodeContext *s, int nb_components, int Ah,
                              int Al, const uint8_t *mb_bitmask,
                              const AVFrame *reference)
@@ -1010,8 +1025,8 @@ static int mjpeg_decode_scan(MJpegDecodeContext *s, int nb_components, int Ah,
                     ptr = data[c] + block_offset;
                     if (!s->progressive) {
                         if (copy_mb)
-                            copy_block8(ptr, reference_data[c] + block_offset,
-                                        linesize[c], linesize[c], 8);
+                            mjpeg_copy_block(ptr, reference_data[c] + block_offset,
+                                             linesize[c], s->avctx->lowres);
                         else {
                             s->dsp.clear_block(s->block);
                             if (decode_block(s, s->block, i,

libavcodec/mpeg12.c

@@ -1676,6 +1676,7 @@ static int mpeg_decode_slice(MpegEncContext *s, int mb_y,
                              const uint8_t **buf, int buf_size)
 {
     AVCodecContext *avctx = s->avctx;
+    const int lowres      = s->avctx->lowres;
     const int field_pic   = s->picture_structure != PICT_FRAME;
 
     s->resync_mb_x =
@@ -1798,14 +1799,14 @@ static int mpeg_decode_slice(MpegEncContext *s, int mb_y,
             }
         }
 
-        s->dest[0] += 16;
-        s->dest[1] += 16 >> s->chroma_x_shift;
-        s->dest[2] += 16 >> s->chroma_x_shift;
+        s->dest[0] += 16 >> lowres;
+        s->dest[1] +=(16 >> lowres) >> s->chroma_x_shift;
+        s->dest[2] +=(16 >> lowres) >> s->chroma_x_shift;
 
         ff_MPV_decode_mb(s, s->block);
 
         if (++s->mb_x >= s->mb_width) {
-            const int mb_size = 16;
+            const int mb_size = 16 >> s->avctx->lowres;
 
             ff_draw_horiz_band(s, mb_size*(s->mb_y >> field_pic), mb_size);
             ff_MPV_report_decode_progress(s);
@@ -2590,6 +2591,7 @@ AVCodec ff_mpeg1video_decoder = {
                              CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY |
                              CODEC_CAP_SLICE_THREADS,
     .flush                 = flush,
+    .max_lowres            = 3,
     .long_name             = NULL_IF_CONFIG_SMALL("MPEG-1 video"),
     .update_thread_context = ONLY_IF_THREADS_ENABLED(mpeg_decode_update_thread_context)
 };
@@ -2606,6 +2608,7 @@ AVCodec ff_mpeg2video_decoder = {
                       CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY |
                       CODEC_CAP_SLICE_THREADS,
     .flush          = flush,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-2 video"),
     .profiles       = NULL_IF_CONFIG_SMALL(mpeg2_video_profiles),
 };

libavcodec/mpeg4videodec.c

@@ -2343,6 +2343,7 @@ AVCodec ff_mpeg4_decoder = {
                              CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY |
                              CODEC_CAP_FRAME_THREADS,
     .flush                 = ff_mpeg_flush,
+    .max_lowres            = 3,
     .long_name             = NULL_IF_CONFIG_SMALL("MPEG-4 part 2"),
     .pix_fmts              = ff_hwaccel_pixfmt_list_420,
     .profiles              = NULL_IF_CONFIG_SMALL(mpeg4_video_profiles),

libavcodec/mpegvideo.c

@@ -1784,6 +1784,381 @@ void ff_print_debug_info(MpegEncContext *s, AVFrame *pict)
     }
 }
 
+static inline int hpel_motion_lowres(MpegEncContext *s,
+                                     uint8_t *dest, uint8_t *src,
+                                     int field_based, int field_select,
+                                     int src_x, int src_y,
+                                     int width, int height, int stride,
+                                     int h_edge_pos, int v_edge_pos,
+                                     int w, int h, h264_chroma_mc_func *pix_op,
+                                     int motion_x, int motion_y)
+{
+    const int lowres   = s->avctx->lowres;
+    const int op_index = FFMIN(lowres, 2);
+    const int s_mask   = (2 << lowres) - 1;
+    int emu = 0;
+    int sx, sy;
+
+    if (s->quarter_sample) {
+        motion_x /= 2;
+        motion_y /= 2;
+    }
+
+    sx = motion_x & s_mask;
+    sy = motion_y & s_mask;
+    src_x += motion_x >> lowres + 1;
+    src_y += motion_y >> lowres + 1;
+
+    src   += src_y * stride + src_x;
+
+    if ((unsigned)src_x > FFMAX( h_edge_pos - (!!sx) - w,                 0) ||
+        (unsigned)src_y > FFMAX((v_edge_pos >> field_based) - (!!sy) - h, 0)) {
+        s->dsp.emulated_edge_mc(s->edge_emu_buffer, src, s->linesize, w + 1,
+                                (h + 1) << field_based, src_x,
+                                src_y   << field_based,
+                                h_edge_pos,
+                                v_edge_pos);
+        src = s->edge_emu_buffer;
+        emu = 1;
+    }
+
+    sx = (sx << 2) >> lowres;
+    sy = (sy << 2) >> lowres;
+    if (field_select)
+        src += s->linesize;
+    pix_op[op_index](dest, src, stride, h, sx, sy);
+    return emu;
+}
+
+/* apply one mpeg motion vector to the three components */
+static av_always_inline void mpeg_motion_lowres(MpegEncContext *s,
+                                                uint8_t *dest_y,
+                                                uint8_t *dest_cb,
+                                                uint8_t *dest_cr,
+                                                int field_based,
+                                                int bottom_field,
+                                                int field_select,
+                                                uint8_t **ref_picture,
+                                                h264_chroma_mc_func *pix_op,
+                                                int motion_x, int motion_y,
+                                                int h, int mb_y)
+{
+    uint8_t *ptr_y, *ptr_cb, *ptr_cr;
+    int mx, my, src_x, src_y, uvsrc_x, uvsrc_y, uvlinesize, linesize, sx, sy,
+        uvsx, uvsy;
+    const int lowres     = s->avctx->lowres;
+    const int op_index   = FFMIN(lowres-1+s->chroma_x_shift, 2);
+    const int block_s    = 8>>lowres;
+    const int s_mask     = (2 << lowres) - 1;
+    const int h_edge_pos = s->h_edge_pos >> lowres;
+    const int v_edge_pos = s->v_edge_pos >> lowres;
+    linesize   = s->current_picture.f.linesize[0] << field_based;
+    uvlinesize = s->current_picture.f.linesize[1] << field_based;
+
+    // FIXME obviously not perfect but qpel will not work in lowres anyway
+    if (s->quarter_sample) {
+        motion_x /= 2;
+        motion_y /= 2;
+    }
+
+    if(field_based){
+        motion_y += (bottom_field - field_select)*((1 << lowres)-1);
+    }
+
+    sx = motion_x & s_mask;
+    sy = motion_y & s_mask;
+    src_x = s->mb_x * 2 * block_s + (motion_x >> lowres + 1);
+    src_y = (mb_y * 2 * block_s >> field_based) + (motion_y >> lowres + 1);
+
+    if (s->out_format == FMT_H263) {
+        uvsx    = ((motion_x >> 1) & s_mask) | (sx & 1);
+        uvsy    = ((motion_y >> 1) & s_mask) | (sy & 1);
+        uvsrc_x = src_x >> 1;
+        uvsrc_y = src_y >> 1;
+    } else if (s->out_format == FMT_H261) {
+        // even chroma mv's are full pel in H261
+        mx      = motion_x / 4;
+        my      = motion_y / 4;
+        uvsx    = (2 * mx) & s_mask;
+        uvsy    = (2 * my) & s_mask;
+        uvsrc_x = s->mb_x * block_s + (mx >> lowres);
+        uvsrc_y =    mb_y * block_s + (my >> lowres);
+    } else {
+        if(s->chroma_y_shift){
+            mx      = motion_x / 2;
+            my      = motion_y / 2;
+            uvsx    = mx & s_mask;
+            uvsy    = my & s_mask;
+            uvsrc_x = s->mb_x * block_s                 + (mx >> lowres + 1);
+            uvsrc_y =   (mb_y * block_s >> field_based) + (my >> lowres + 1);
+        } else {
+            if(s->chroma_x_shift){
+            //Chroma422
+                mx = motion_x / 2;
+                uvsx = mx & s_mask;
+                uvsy = motion_y & s_mask;
+                uvsrc_y = src_y;
+                uvsrc_x = s->mb_x*block_s               + (mx >> (lowres+1));
+            } else {
+            //Chroma444
+                uvsx = motion_x & s_mask;
+                uvsy = motion_y & s_mask;
+                uvsrc_x = src_x;
+                uvsrc_y = src_y;
+            }
+        }
+    }
+
+    ptr_y  = ref_picture[0] + src_y   * linesize   + src_x;
+    ptr_cb = ref_picture[1] + uvsrc_y * uvlinesize + uvsrc_x;
+    ptr_cr = ref_picture[2] + uvsrc_y * uvlinesize + uvsrc_x;
+
+    if ((unsigned) src_x > FFMAX( h_edge_pos - (!!sx) - 2 * block_s,       0) ||
+        (unsigned) src_y > FFMAX((v_edge_pos >> field_based) - (!!sy) - h, 0)) {
+        s->dsp.emulated_edge_mc(s->edge_emu_buffer, ptr_y,
+                                s->linesize, 17, 17 + field_based,
+                                src_x, src_y << field_based, h_edge_pos,
+                                v_edge_pos);
+        ptr_y = s->edge_emu_buffer;
+        if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY)) {
+            uint8_t *uvbuf = s->edge_emu_buffer + 18 * s->linesize;
+            s->dsp.emulated_edge_mc(uvbuf , ptr_cb, s->uvlinesize, 9,
+                                    9 + field_based,
+                                    uvsrc_x, uvsrc_y << field_based,
+                                    h_edge_pos >> 1, v_edge_pos >> 1);
+            s->dsp.emulated_edge_mc(uvbuf + 16, ptr_cr, s->uvlinesize, 9,
+                                    9 + field_based,
+                                    uvsrc_x, uvsrc_y << field_based,
+                                    h_edge_pos >> 1, v_edge_pos >> 1);
+            ptr_cb = uvbuf;
+            ptr_cr = uvbuf + 16;
+        }
+    }
+
+    // FIXME use this for field pix too instead of the obnoxious hack which changes picture.f.data
+    if (bottom_field) {
+        dest_y  += s->linesize;
+        dest_cb += s->uvlinesize;
+        dest_cr += s->uvlinesize;
+    }
+
+    if (field_select) {
+        ptr_y   += s->linesize;
+        ptr_cb  += s->uvlinesize;
+        ptr_cr  += s->uvlinesize;
+    }
+
+    sx = (sx << 2) >> lowres;
+    sy = (sy << 2) >> lowres;
+    pix_op[lowres - 1](dest_y, ptr_y, linesize, h, sx, sy);
+
+    if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY)) {
+        uvsx = (uvsx << 2) >> lowres;
+        uvsy = (uvsy << 2) >> lowres;
+        if (h >> s->chroma_y_shift) {
+            pix_op[op_index](dest_cb, ptr_cb, uvlinesize, h >> s->chroma_y_shift, uvsx, uvsy);
+            pix_op[op_index](dest_cr, ptr_cr, uvlinesize, h >> s->chroma_y_shift, uvsx, uvsy);
+        }
+    }
+    // FIXME h261 lowres loop filter
+}
+
+static inline void chroma_4mv_motion_lowres(MpegEncContext *s,
+                                            uint8_t *dest_cb, uint8_t *dest_cr,
+                                            uint8_t **ref_picture,
+                                            h264_chroma_mc_func * pix_op,
+                                            int mx, int my)
+{
+    const int lowres     = s->avctx->lowres;
+    const int op_index   = FFMIN(lowres, 2);
+    const int block_s    = 8 >> lowres;
+    const int s_mask     = (2 << lowres) - 1;
+    const int h_edge_pos = s->h_edge_pos >> lowres + 1;
+    const int v_edge_pos = s->v_edge_pos >> lowres + 1;
+    int emu = 0, src_x, src_y, offset, sx, sy;
+    uint8_t *ptr;
+
+    if (s->quarter_sample) {
+        mx /= 2;
+        my /= 2;
+    }
+
+    /* In case of 8X8, we construct a single chroma motion vector
+       with a special rounding */
+    mx = ff_h263_round_chroma(mx);
+    my = ff_h263_round_chroma(my);
+
+    sx = mx & s_mask;
+    sy = my & s_mask;
+    src_x = s->mb_x * block_s + (mx >> lowres + 1);
+    src_y = s->mb_y * block_s + (my >> lowres + 1);
+
+    offset = src_y * s->uvlinesize + src_x;
+    ptr = ref_picture[1] + offset;
+    if (s->flags & CODEC_FLAG_EMU_EDGE) {
+        if ((unsigned) src_x > FFMAX(h_edge_pos - (!!sx) - block_s, 0) ||
+            (unsigned) src_y > FFMAX(v_edge_pos - (!!sy) - block_s, 0)) {
+            s->dsp.emulated_edge_mc(s->edge_emu_buffer, ptr, s->uvlinesize,
+                                    9, 9, src_x, src_y, h_edge_pos, v_edge_pos);
+            ptr = s->edge_emu_buffer;
+            emu = 1;
+        }
+    }
+    sx = (sx << 2) >> lowres;
+    sy = (sy << 2) >> lowres;
+    pix_op[op_index](dest_cb, ptr, s->uvlinesize, block_s, sx, sy);
+
+    ptr = ref_picture[2] + offset;
+    if (emu) {
+        s->dsp.emulated_edge_mc(s->edge_emu_buffer, ptr, s->uvlinesize, 9, 9,
+                                src_x, src_y, h_edge_pos, v_edge_pos);
+        ptr = s->edge_emu_buffer;
+    }
+    pix_op[op_index](dest_cr, ptr, s->uvlinesize, block_s, sx, sy);
+}
+
+/**
+ * motion compensation of a single macroblock
+ * @param s context
+ * @param dest_y luma destination pointer
+ * @param dest_cb chroma cb/u destination pointer
+ * @param dest_cr chroma cr/v destination pointer
+ * @param dir direction (0->forward, 1->backward)
+ * @param ref_picture array[3] of pointers to the 3 planes of the reference picture
+ * @param pix_op halfpel motion compensation function (average or put normally)
+ * the motion vectors are taken from s->mv and the MV type from s->mv_type
+ */
+static inline void MPV_motion_lowres(MpegEncContext *s,
+                                     uint8_t *dest_y, uint8_t *dest_cb,
+                                     uint8_t *dest_cr,
+                                     int dir, uint8_t **ref_picture,
+                                     h264_chroma_mc_func *pix_op)
+{
+    int mx, my;
+    int mb_x, mb_y, i;
+    const int lowres  = s->avctx->lowres;
+    const int block_s = 8 >>lowres;
+
+    mb_x = s->mb_x;
+    mb_y = s->mb_y;
+
+    switch (s->mv_type) {
+    case MV_TYPE_16X16:
+        mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
+                           0, 0, 0,
+                           ref_picture, pix_op,
+                           s->mv[dir][0][0], s->mv[dir][0][1],
+                           2 * block_s, mb_y);
+        break;
+    case MV_TYPE_8X8:
+        mx = 0;
+        my = 0;
+        for (i = 0; i < 4; i++) {
+            hpel_motion_lowres(s, dest_y + ((i & 1) + (i >> 1) *
+                               s->linesize) * block_s,
+                               ref_picture[0], 0, 0,
+                               (2 * mb_x + (i & 1)) * block_s,
+                               (2 * mb_y + (i >> 1)) * block_s,
+                               s->width, s->height, s->linesize,
+                               s->h_edge_pos >> lowres, s->v_edge_pos >> lowres,
+                               block_s, block_s, pix_op,
+                               s->mv[dir][i][0], s->mv[dir][i][1]);
+
+            mx += s->mv[dir][i][0];
+            my += s->mv[dir][i][1];
+        }
+
+        if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY))
+            chroma_4mv_motion_lowres(s, dest_cb, dest_cr, ref_picture,
+                                     pix_op, mx, my);
+        break;
+    case MV_TYPE_FIELD:
+        if (s->picture_structure == PICT_FRAME) {
+            /* top field */
+            mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
+                               1, 0, s->field_select[dir][0],
+                               ref_picture, pix_op,
+                               s->mv[dir][0][0], s->mv[dir][0][1],
+                               block_s, mb_y);
+            /* bottom field */
+            mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
+                               1, 1, s->field_select[dir][1],
+                               ref_picture, pix_op,
+                               s->mv[dir][1][0], s->mv[dir][1][1],
+                               block_s, mb_y);
+        } else {
+            if (s->picture_structure != s->field_select[dir][0] + 1 &&
+                s->pict_type != AV_PICTURE_TYPE_B && !s->first_field) {
+                ref_picture = s->current_picture_ptr->f.data;
+
+            }
+            mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
+                               0, 0, s->field_select[dir][0],
+                               ref_picture, pix_op,
+                               s->mv[dir][0][0],
+                               s->mv[dir][0][1], 2 * block_s, mb_y >> 1);
+            }
+        break;
+    case MV_TYPE_16X8:
+        for (i = 0; i < 2; i++) {
+            uint8_t **ref2picture;
+
+            if (s->picture_structure == s->field_select[dir][i] + 1 ||
+                s->pict_type == AV_PICTURE_TYPE_B || s->first_field) {
+                ref2picture = ref_picture;
+            } else {
+                ref2picture = s->current_picture_ptr->f.data;
+            }
+
+            mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
+                               0, 0, s->field_select[dir][i],
+                               ref2picture, pix_op,
+                               s->mv[dir][i][0], s->mv[dir][i][1] +
+                               2 * block_s * i, block_s, mb_y >> 1);
+
+            dest_y  +=  2 * block_s *  s->linesize;
+            dest_cb += (2 * block_s >> s->chroma_y_shift) * s->uvlinesize;
+            dest_cr += (2 * block_s >> s->chroma_y_shift) * s->uvlinesize;
+        }
+        break;
+    case MV_TYPE_DMV:
+        if (s->picture_structure == PICT_FRAME) {
+            for (i = 0; i < 2; i++) {
+                int j;
+                for (j = 0; j < 2; j++) {
+                    mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
+                                       1, j, j ^ i,
+                                       ref_picture, pix_op,
+                                       s->mv[dir][2 * i + j][0],
+                                       s->mv[dir][2 * i + j][1],
+                                       block_s, mb_y);
+                }
+                pix_op = s->dsp.avg_h264_chroma_pixels_tab;
+            }
+        } else {
+            for (i = 0; i < 2; i++) {
+                mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
+                                   0, 0, s->picture_structure != i + 1,
+                                   ref_picture, pix_op,
+                                   s->mv[dir][2 * i][0],s->mv[dir][2 * i][1],
+                                   2 * block_s, mb_y >> 1);
+
+                // after put we make avg of the same block
+                pix_op = s->dsp.avg_h264_chroma_pixels_tab;
+
+                // opposite parity is always in the same
+                // frame if this is second field
+                if (!s->first_field) {
+                    ref_picture = s->current_picture_ptr->f.data;
+                }
+            }
+        }
+        break;
+    default:
+        assert(0);
+    }
+}
+
 /**
  * find the lowest MB row referenced in the MVs
  */
@@ -1893,7 +2268,7 @@ void ff_clean_intra_table_entries(MpegEncContext *s)
  */
 static av_always_inline
 void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64],
-                            int is_mpeg12)
+                            int lowres_flag, int is_mpeg12)
 {
     const int mb_xy = s->mb_y * s->mb_stride + s->mb_x;
     if(CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration){
@@ -1938,8 +2313,8 @@ void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64],
         qpel_mc_func (*op_qpix)[16];
         const int linesize   = s->current_picture.f.linesize[0]; //not s->linesize as this would be wrong for field pics
         const int uvlinesize = s->current_picture.f.linesize[1];
-        const int readable= s->pict_type != AV_PICTURE_TYPE_B || s->encoding || s->avctx->draw_horiz_band || s->avctx->lowres;
-        const int block_size= 8 >> s->avctx->lowres;
+        const int readable= s->pict_type != AV_PICTURE_TYPE_B || s->encoding || s->avctx->draw_horiz_band || lowres_flag;
+        const int block_size= lowres_flag ? 8>>s->avctx->lowres : 8;
 
         /* avoid copy if macroblock skipped in last frame too */
         /* skip only during decoding as we might trash the buffers during encoding a bit */
@@ -1988,19 +2363,31 @@ void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64],
                     }
                 }
 
-                op_qpix= s->me.qpel_put;
-                if ((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
-                    op_pix = s->dsp.put_pixels_tab;
+                if(lowres_flag){
+                    h264_chroma_mc_func *op_pix = s->dsp.put_h264_chroma_pixels_tab;
+
+                    if (s->mv_dir & MV_DIR_FORWARD) {
+                        MPV_motion_lowres(s, dest_y, dest_cb, dest_cr, 0, s->last_picture.f.data, op_pix);
+                        op_pix = s->dsp.avg_h264_chroma_pixels_tab;
+                    }
+                    if (s->mv_dir & MV_DIR_BACKWARD) {
+                        MPV_motion_lowres(s, dest_y, dest_cb, dest_cr, 1, s->next_picture.f.data, op_pix);
+                    }
                 }else{
-                    op_pix = s->dsp.put_no_rnd_pixels_tab;
-                }
-                if (s->mv_dir & MV_DIR_FORWARD) {
-                    MPV_motion(s, dest_y, dest_cb, dest_cr, 0, s->last_picture.f.data, op_pix, op_qpix);
-                    op_pix = s->dsp.avg_pixels_tab;
-                    op_qpix= s->me.qpel_avg;
-                }
-                if (s->mv_dir & MV_DIR_BACKWARD) {
-                    MPV_motion(s, dest_y, dest_cb, dest_cr, 1, s->next_picture.f.data, op_pix, op_qpix);
+                    op_qpix= s->me.qpel_put;
+                    if ((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
+                        op_pix = s->dsp.put_pixels_tab;
+                    }else{
+                        op_pix = s->dsp.put_no_rnd_pixels_tab;
+                    }
+                    if (s->mv_dir & MV_DIR_FORWARD) {
+                        MPV_motion(s, dest_y, dest_cb, dest_cr, 0, s->last_picture.f.data, op_pix, op_qpix);
+                        op_pix = s->dsp.avg_pixels_tab;
+                        op_qpix= s->me.qpel_avg;
+                    }
+                    if (s->mv_dir & MV_DIR_BACKWARD) {
+                        MPV_motion(s, dest_y, dest_cb, dest_cr, 1, s->next_picture.f.data, op_pix, op_qpix);
+                    }
                 }
             }
 
@@ -2016,9 +2403,9 @@ void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64],
             if(s->encoding || !(   s->msmpeg4_version || s->codec_id==CODEC_ID_MPEG1VIDEO || s->codec_id==CODEC_ID_MPEG2VIDEO
                                 || (s->codec_id==CODEC_ID_MPEG4 && !s->mpeg_quant))){
                 add_dequant_dct(s, block[0], 0, dest_y                          , dct_linesize, s->qscale);
-                add_dequant_dct(s, block[1], 1, dest_y              + 8         , dct_linesize, s->qscale);
+                add_dequant_dct(s, block[1], 1, dest_y              + block_size, dct_linesize, s->qscale);
                 add_dequant_dct(s, block[2], 2, dest_y + dct_offset             , dct_linesize, s->qscale);
-                add_dequant_dct(s, block[3], 3, dest_y + dct_offset + 8         , dct_linesize, s->qscale);
+                add_dequant_dct(s, block[3], 3, dest_y + dct_offset + block_size, dct_linesize, s->qscale);
 
                 if(!CONFIG_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
                     if (s->chroma_y_shift){
@@ -2035,9 +2422,9 @@ void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64],
                 }
             } else if(is_mpeg12 || (s->codec_id != CODEC_ID_WMV2)){
                 add_dct(s, block[0], 0, dest_y                          , dct_linesize);
-                add_dct(s, block[1], 1, dest_y              + 8         , dct_linesize);
+                add_dct(s, block[1], 1, dest_y              + block_size, dct_linesize);
                 add_dct(s, block[2], 2, dest_y + dct_offset             , dct_linesize);
-                add_dct(s, block[3], 3, dest_y + dct_offset + 8         , dct_linesize);
+                add_dct(s, block[3], 3, dest_y + dct_offset + block_size, dct_linesize);
 
                 if(!CONFIG_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
                     if(s->chroma_y_shift){//Chroma420
@@ -2046,17 +2433,17 @@ void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64],
                     }else{
                         //chroma422
                         dct_linesize = uvlinesize << s->interlaced_dct;
-                        dct_offset   = s->interlaced_dct ? uvlinesize : uvlinesize*8;
+                        dct_offset   = s->interlaced_dct ? uvlinesize : uvlinesize*block_size;
 
                         add_dct(s, block[4], 4, dest_cb, dct_linesize);
                         add_dct(s, block[5], 5, dest_cr, dct_linesize);
                         add_dct(s, block[6], 6, dest_cb+dct_offset, dct_linesize);
                         add_dct(s, block[7], 7, dest_cr+dct_offset, dct_linesize);
                         if(!s->chroma_x_shift){//Chroma444
-                            add_dct(s, block[8], 8, dest_cb+8, dct_linesize);
-                            add_dct(s, block[9], 9, dest_cr+8, dct_linesize);
-                            add_dct(s, block[10], 10, dest_cb+8+dct_offset, dct_linesize);
-                            add_dct(s, block[11], 11, dest_cr+8+dct_offset, dct_linesize);
+                            add_dct(s, block[8], 8, dest_cb+block_size, dct_linesize);
+                            add_dct(s, block[9], 9, dest_cr+block_size, dct_linesize);
+                            add_dct(s, block[10], 10, dest_cb+block_size+dct_offset, dct_linesize);
+                            add_dct(s, block[11], 11, dest_cr+block_size+dct_offset, dct_linesize);
                         }
                     }
                 }//fi gray
@@ -2087,9 +2474,9 @@ void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64],
                 }
             }else{
                 s->dsp.idct_put(dest_y                          , dct_linesize, block[0]);
-                s->dsp.idct_put(dest_y              + 8         , dct_linesize, block[1]);
+                s->dsp.idct_put(dest_y              + block_size, dct_linesize, block[1]);
                 s->dsp.idct_put(dest_y + dct_offset             , dct_linesize, block[2]);
-                s->dsp.idct_put(dest_y + dct_offset + 8         , dct_linesize, block[3]);
+                s->dsp.idct_put(dest_y + dct_offset + block_size, dct_linesize, block[3]);
 
                 if(!CONFIG_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
                     if(s->chroma_y_shift){
@@ -2098,17 +2485,17 @@ void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64],
                     }else{
 
                         dct_linesize = uvlinesize << s->interlaced_dct;
-                        dct_offset   = s->interlaced_dct? uvlinesize : uvlinesize*8;
+                        dct_offset   = s->interlaced_dct? uvlinesize : uvlinesize*block_size;
 
                         s->dsp.idct_put(dest_cb,              dct_linesize, block[4]);
                         s->dsp.idct_put(dest_cr,              dct_linesize, block[5]);
                         s->dsp.idct_put(dest_cb + dct_offset, dct_linesize, block[6]);
                         s->dsp.idct_put(dest_cr + dct_offset, dct_linesize, block[7]);
                         if(!s->chroma_x_shift){//Chroma444
-                            s->dsp.idct_put(dest_cb + 8,              dct_linesize, block[8]);
-                            s->dsp.idct_put(dest_cr + 8,              dct_linesize, block[9]);
-                            s->dsp.idct_put(dest_cb + 8 + dct_offset, dct_linesize, block[10]);
-                            s->dsp.idct_put(dest_cr + 8 + dct_offset, dct_linesize, block[11]);
+                            s->dsp.idct_put(dest_cb + block_size,              dct_linesize, block[8]);
+                            s->dsp.idct_put(dest_cr + block_size,              dct_linesize, block[9]);
+                            s->dsp.idct_put(dest_cb + block_size + dct_offset, dct_linesize, block[10]);
+                            s->dsp.idct_put(dest_cr + block_size + dct_offset, dct_linesize, block[11]);
                         }
                     }
                 }//gray
@@ -2126,10 +2513,12 @@ skip_idct:
 void ff_MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64]){
 #if !CONFIG_SMALL
     if(s->out_format == FMT_MPEG1) {
-        MPV_decode_mb_internal(s, block, 1);
+        if(s->avctx->lowres) MPV_decode_mb_internal(s, block, 1, 1);
+        else                 MPV_decode_mb_internal(s, block, 0, 1);
     } else
 #endif
-        MPV_decode_mb_internal(s, block, 0);
+    if(s->avctx->lowres) MPV_decode_mb_internal(s, block, 1, 0);
+    else                  MPV_decode_mb_internal(s, block, 0, 0);
 }
 
 /**

libavcodec/msmpeg4.c

@@ -1216,6 +1216,7 @@ AVCodec ff_msmpeg4v1_decoder = {
     .close          = ff_h263_decode_end,
     .decode         = ff_h263_decode_frame,
     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-4 part 2 Microsoft variant version 1"),
     .pix_fmts       = ff_pixfmt_list_420,
 };
@@ -1229,6 +1230,7 @@ AVCodec ff_msmpeg4v2_decoder = {
     .close          = ff_h263_decode_end,
     .decode         = ff_h263_decode_frame,
     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-4 part 2 Microsoft variant version 2"),
     .pix_fmts       = ff_pixfmt_list_420,
 };
@@ -1242,6 +1244,7 @@ AVCodec ff_msmpeg4v3_decoder = {
     .close          = ff_h263_decode_end,
     .decode         = ff_h263_decode_frame,
     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-4 part 2 Microsoft variant version 3"),
     .pix_fmts       = ff_pixfmt_list_420,
 };
@@ -1255,6 +1258,7 @@ AVCodec ff_wmv1_decoder = {
     .close          = ff_h263_decode_end,
     .decode         = ff_h263_decode_frame,
     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("Windows Media Video 7"),
     .pix_fmts       = ff_pixfmt_list_420,
 };

libavcodec/mxpegdec.c

@@ -339,4 +339,5 @@ AVCodec ff_mxpeg_decoder = {
     .close          = mxpeg_decode_end,
     .decode         = mxpeg_decode_frame,
     .capabilities   = CODEC_CAP_DR1,
+    .max_lowres     = 3,
 };

libavcodec/rv10.c

@@ -435,7 +435,8 @@ av_log(s->avctx, AV_LOG_DEBUG, "\n");*/
 //    s->obmc=1;
 //    s->umvplus=1;
     s->modified_quant=1;
-    s->loop_filter=1;
+    if(!s->avctx->lowres)
+        s->loop_filter=1;
 
     if(s->avctx->debug & FF_DEBUG_PICT_INFO){
             av_log(s->avctx, AV_LOG_INFO, "num:%5d x:%2d y:%2d type:%d qscale:%2d rnd:%d\n",
@@ -754,6 +755,7 @@ AVCodec ff_rv10_decoder = {
     .close          = rv10_decode_end,
     .decode         = rv10_decode_frame,
     .capabilities   = CODEC_CAP_DR1,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("RealVideo 1.0"),
     .pix_fmts       = ff_pixfmt_list_420,
 };
@@ -768,6 +770,7 @@ AVCodec ff_rv20_decoder = {
     .decode         = rv10_decode_frame,
     .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_DELAY,
     .flush          = ff_mpeg_flush,
+    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("RealVideo 2.0"),
     .pix_fmts       = ff_pixfmt_list_420,
 };