avcodec/mpegvideo_dec: Simplify check for unquantizing inter blocks

Just ensure that dct_unquantize_inter is set iff it is used and check for the function pointer instead.

Andreas Rheinhardt committed 1 year ago

Commit 778c0a41 parent f2c04fd5 files · +14 −8Browse files

Showing the changes to libavcodec (5 of 5 files). Show all

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@@ -110,7 +110,8 @@ av_cold int ff_h263_decode_init(AVCodecContext *avctx) · 109 unmodified lines
110	ff_mpv_unquantize_init(&unquant_dsp_ctx,	110	ff_mpv_unquantize_init(&unquant_dsp_ctx,
111	avctx->flags & AV_CODEC_FLAG_BITEXACT, 0);	111	avctx->flags & AV_CODEC_FLAG_BITEXACT, 0);
112	// dct_unquantize defaults for H.263;	112	// dct_unquantize defaults for H.263;
113	// they might change on a per-frame basis for MPEG-4.	113	// they might change on a per-frame basis for MPEG-4;
		114	// dct_unquantize_inter will be unset for MSMPEG4 codecs later.
114	s->dct_unquantize_intra = unquant_dsp_ctx.dct_unquantize_h263_intra;	115	s->dct_unquantize_intra = unquant_dsp_ctx.dct_unquantize_h263_intra;
115	s->dct_unquantize_inter = unquant_dsp_ctx.dct_unquantize_h263_inter;	116	s->dct_unquantize_inter = unquant_dsp_ctx.dct_unquantize_h263_inter;
116		117

     s->dct_unquantize_intra = s->mpeg_quant ? ctx->dct_unquantize_mpeg2_intra
                                             : ctx->dct_unquantize_h263_intra;
+    // The following tells ff_mpv_reconstruct_mb() to unquantize iff mpeg_quant
+    s->dct_unquantize_inter = s->mpeg_quant ? ctx->dct_unquantize_mpeg2_inter : NULL;
 end:
     /* detect buggy encoders which don't set the low_delay flag
     ctx->dct_unquantize_h263_intra  = unquant_dsp_ctx.dct_unquantize_h263_intra;
     ctx->dct_unquantize_mpeg2_intra = unquant_dsp_ctx.dct_unquantize_mpeg2_intra;
     // dct_unquantize_inter is only used with MPEG-2 quantizers,
-    // so we can already set dct_unquantize_inter here once and for all.
+    // so that is all we keep.
-    s->dct_unquantize_inter = unquant_dsp_ctx.dct_unquantize_mpeg2_inter;
+    ctx->dct_unquantize_mpeg2_inter = unquant_dsp_ctx.dct_unquantize_mpeg2_inter;
     s->y_dc_scale_table = ff_mpeg4_y_dc_scale_table;
     s->c_dc_scale_table = ff_mpeg4_c_dc_scale_table;

@@ -91,6 +91,8 @@ typedef struct Mpeg4DecContext { · 90 unmodified lines
91		91
92	Mpeg4VideoDSPContext mdsp;	92	Mpeg4VideoDSPContext mdsp;
93		93
		94	void (dct_unquantize_mpeg2_inter)(MpegEncContext s,
		95	int16_t *block, int n, int qscale);
94	void (dct_unquantize_mpeg2_intra)(MpegEncContext s,	96	void (dct_unquantize_mpeg2_intra)(MpegEncContext s,
95	int16_t *block, int n, int qscale);	97	int16_t *block, int n, int qscale);
96	void (dct_unquantize_h263_intra)(MpegEncContext s,	98	void (dct_unquantize_h263_intra)(MpegEncContext s,

         }
         /* add dct residue */
-        if (!(IS_MPEG12_H261(s) || s->msmpeg4_version != MSMP4_UNUSED ||
+        if (is_mpeg12 != DEFINITELY_MPEG12_H261 && s->dct_unquantize_inter) {
-              (s->codec_id == AV_CODEC_ID_MPEG4 && !s->mpeg_quant))) {
             // H.263, H.263+, H.263I, FLV, RV10, RV20 and MPEG-4 with MPEG-2 quantization
-            // Also RV30, RV40 when performing error resilience, but
-            // all blocks are skipped in this case.
             add_dequant_dct(s, block[0], 0, dest_y                          , 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);
         } else if (is_mpeg12 == DEFINITELY_MPEG12_H261 || lowres_flag || (s->codec_id != AV_CODEC_ID_WMV2)) {
             // H.261, MPEG-1, MPEG-2, MPEG-4 with H.263 quantization,
             // MSMP4V1-3 and WMV1.
-            // Also the VC-1 family when performing error resilience
+            // Also RV30, RV40 and the VC-1 family when performing error resilience,
+            // but all blocks are skipped in this case.
             add_dct(s, block[0], 0, dest_y                          , 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);

@@ -366,6 +366,9 @@ av_cold int ff_msmpeg4_decode_init(AVCodecContext *avctx) · 365 unmodified lines
366	if (ff_h263_decode_init(avctx) < 0)	366	if (ff_h263_decode_init(avctx) < 0)
367	return -1;	367	return -1;
368		368
		369	// We unquantize inter blocks as we parse them.
		370	s->dct_unquantize_inter = NULL;
		371
369	ff_msmpeg4_common_init(s);	372	ff_msmpeg4_common_init(s);
370		373
371	switch (s->msmpeg4_version) {	374	switch (s->msmpeg4_version) {

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