[FFmpeg-devel] Fwd: [PATCH v2] avcodec/h264: fixed qp table attach for h264

[Timothee <timothee.informatique@regaud-chapuy.fr>]

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Hello,

Thank you for the feedback on my first patch. The corruption was likely 
caused by my email client's text formatting.

The patch is attach to prevent any formatting error.

I have check the patch file applies cleanly using `git am` and verified 
that all FATE tests still pass.

Please let me know if this version is correct. Any advice is welcome.

Thanks,
Timothée

On 13/06/2025 à 22:52, Michael Niedermayer wrote :
> On Fri, Jun 13, 2025 at 02:37:53PM +0200, Timothee wrote:
>> Hello,
>>
>> Here is a patch where I fixed the attach of per-macroblock qp tables for
>> H.264. It was implemented for MPEG2 so I have only extended it.
>>
>> I tested the functionality with the codecview filter using the following
>> command: `./ffmpeg -export_side_data 4 -i input.mp4 -vf codecview=qp=1
>> output.mp4`
>>
>> FATE passes.
>>
>> Thanks,
>> Timothée
>>
>> Signed-off-by: Timothee <timothee.informatique@regaud-chapuy.fr>
>> ---
>> libavcodec/h264_slice.c | 16 ++++++++++++----
>> libavfilter/qp_table.c | 3 ++-
>> libavfilter/qp_table.h | 1 +
>> 3 files changed, 15 insertions(+), 5 deletions(-)
>>
>> diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
>> index 7e53e38cca..f217c58837 100644
>> --- a/libavcodec/h264_slice.c
>> +++ b/libavcodec/h264_slice.c
>> @@ -2615,8 +2615,10 @@ static int decode_slice(struct AVCodecContext 
>> *avctx,
>> void *arg)
>> ret = ff_h264_decode_mb_cabac(h, sl);
>> - if (ret >= 0)
>> + if (ret >= 0) {
> Applying: avcodec/h264: fixed qp table attach for h264
> error: corrupt patch at line 20
> error: could not build fake ancestor
>
> [...]
>
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From 422e8dbdc3d79b24c6ccb11b7f384fc08406ee74 Mon Sep 17 00:00:00 2001
From: Timothee <timothee.informatique@regaud-chapuy.fr>
Date: Fri, 13 Jun 2025 14:21:28 +0200
Subject: [PATCH] avcodec/h264: fixed qp table attach for h264

Signed-off-by: Timothee <timothee.informatique@regaud-chapuy.fr>
---
 libavcodec/h264_slice.c | 16 ++++++++++++----
 libavfilter/qp_table.c  |  3 ++-
 libavfilter/qp_table.h  |  1 +
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
index 7e53e38cca..f217c58837 100644
--- a/libavcodec/h264_slice.c
+++ b/libavcodec/h264_slice.c
@@ -2615,8 +2615,10 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
 
             ret = ff_h264_decode_mb_cabac(h, sl);
 
-            if (ret >= 0)
+            if (ret >= 0) {
                 ff_h264_hl_decode_mb(h, sl);
+                h->cur_pic.qscale_table[sl->mb_xy] = sl->qscale;
+            }
 
             // FIXME optimal? or let mb_decode decode 16x32 ?
             if (ret >= 0 && FRAME_MBAFF(h)) {
@@ -2624,8 +2626,10 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
 
                 ret = ff_h264_decode_mb_cabac(h, sl);
 
-                if (ret >= 0)
+                if (ret >= 0) {
                     ff_h264_hl_decode_mb(h, sl);
+                    h->cur_pic.qscale_table[sl->mb_xy] = sl->qscale;
+                }
                 sl->mb_y--;
             }
             eos = get_cabac_terminate(&sl->cabac);
@@ -2686,16 +2690,20 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
 
             ret = ff_h264_decode_mb_cavlc(h, sl);
 
-            if (ret >= 0)
+            if (ret >= 0) {
                 ff_h264_hl_decode_mb(h, sl);
+                h->cur_pic.qscale_table[sl->mb_xy] = sl->qscale;
+            }
 
             // FIXME optimal? or let mb_decode decode 16x32 ?
             if (ret >= 0 && FRAME_MBAFF(h)) {
                 sl->mb_y++;
                 ret = ff_h264_decode_mb_cavlc(h, sl);
 
-                if (ret >= 0)
+                if (ret >= 0) {
                     ff_h264_hl_decode_mb(h, sl);
+                    h->cur_pic.qscale_table[sl->mb_xy] = sl->qscale;
+                }
                 sl->mb_y--;
             }
 
diff --git a/libavfilter/qp_table.c b/libavfilter/qp_table.c
index 8137dc019f..a99b99e77a 100644
--- a/libavfilter/qp_table.c
+++ b/libavfilter/qp_table.c
@@ -40,7 +40,8 @@ int ff_qp_table_extract(AVFrame *frame, int8_t **table, int *table_w, int *table
     if (!sd)
         return 0;
     par = (AVVideoEncParams*)sd->data;
-    if (par->type != AV_VIDEO_ENC_PARAMS_MPEG2 ||
+    if ((par->type != AV_VIDEO_ENC_PARAMS_MPEG2
+       && par->type != AV_VIDEO_ENC_PARAMS_H264) ||
         (par->nb_blocks != 0 && par->nb_blocks != nb_mb))
         return AVERROR(ENOSYS);
 
diff --git a/libavfilter/qp_table.h b/libavfilter/qp_table.h
index 4407bacb0e..c1a80d1830 100644
--- a/libavfilter/qp_table.h
+++ b/libavfilter/qp_table.h
@@ -40,6 +40,7 @@ static inline int ff_norm_qscale(int qscale, enum AVVideoEncParamsType type)
 {
     switch (type) {
     case AV_VIDEO_ENC_PARAMS_MPEG2: return qscale >> 1;
+    case AV_VIDEO_ENC_PARAMS_H264:  return qscale;
     }
     return qscale;
 }
-- 
2.39.5


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