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/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,
 };