h264: Integrate draw_horiz_band into ff_h264_draw_horiz_band

This makes the decoder independent of mpegvideo.

This copy of the draw_horiz_band code is simplified compared to
the "generic" mpegvideo one which still has a number of special
cases for different codecs.
Signed-off-by: Martin Storsjö <martin@martin.st>

configure

@@ -1542,7 +1542,7 @@ h263_decoder_select="error_resilience h263_parser mpegvideo"
 h263_encoder_select="aandcttables error_resilience mpegvideoenc"
 h263i_decoder_select="h263_decoder"
 h263p_encoder_select="h263_encoder"
-h264_decoder_select="error_resilience golomb h264chroma h264dsp h264pred h264qpel mpegvideo"
+h264_decoder_select="error_resilience golomb h264chroma h264dsp h264pred h264qpel videodsp"
 huffyuv_encoder_select="huffman"
 iac_decoder_select="fft mdct sinewin"
 imc_decoder_select="fft mdct sinewin"
@@ -1689,7 +1689,7 @@ wmv3_vdpau_decoder_select="vc1_vdpau_decoder"
 wmv3_vdpau_hwaccel_select="vc1_vdpau_hwaccel"
 
 # parsers
-h264_parser_select="error_resilience golomb h264chroma h264dsp h264pred h264qpel mpegvideo"
+h264_parser_select="error_resilience golomb h264chroma h264dsp h264pred h264qpel videodsp"
 mpeg4video_parser_select="error_resilience mpegvideo"
 mpegvideo_parser_select="error_resilience mpegvideo"
 vc1_parser_select="error_resilience mpegvideo"

libavcodec/h264.c

@@ -123,10 +123,46 @@ static void h264_er_decode_mb(void *opaque, int ref, int mv_dir, int mv_type,
 
 void ff_h264_draw_horiz_band(H264Context *h, int y, int height)
 {
-    ff_draw_horiz_band(h->avctx, NULL, &h->cur_pic,
-                       h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0] : NULL,
-                       y, height, h->picture_structure, h->first_field, 0,
-                       h->low_delay, h->mb_height * 16, h->mb_width * 16);
+    AVCodecContext *avctx = h->avctx;
+    Picture *cur  = &h->cur_pic;
+    Picture *last = h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0] : NULL;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
+    int vshift = desc->log2_chroma_h;
+    const int field_pic = h->picture_structure != PICT_FRAME;
+    if (field_pic) {
+        height <<= 1;
+        y <<= 1;
+    }
+
+    height = FFMIN(height, avctx->height - y);
+
+    if (field_pic && h->first_field && !(avctx->slice_flags & SLICE_FLAG_ALLOW_FIELD))
+        return;
+
+    if (avctx->draw_horiz_band) {
+        AVFrame *src;
+        int offset[AV_NUM_DATA_POINTERS];
+        int i;
+
+        if (cur->f.pict_type == AV_PICTURE_TYPE_B || h->low_delay ||
+           (avctx->slice_flags & SLICE_FLAG_CODED_ORDER))
+            src = &cur->f;
+        else if (last)
+            src = &last->f;
+        else
+            return;
+
+        offset[0] = y * src->linesize[0];
+        offset[1] =
+        offset[2] = (y >> vshift) * src->linesize[1];
+        for (i = 3; i < AV_NUM_DATA_POINTERS; i++)
+            offset[i] = 0;
+
+        emms_c();
+
+        avctx->draw_horiz_band(avctx, src, offset,
+                               y, h->picture_structure, height);
+    }
 }
 
 static void free_frame_buffer(H264Context *h, Picture *pic)