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[FFmpeg-devel,1/3] avcodec/avs3_parser: set has_b_frames properly

Message ID tencent_BFE29A959F3AAB9F4EA770E02D6B9A3B4008@qq.com
State New
Headers show
Series [FFmpeg-devel,1/3] avcodec/avs3_parser: set has_b_frames properly | expand

Checks

Context Check Description
andriy/make_x86 success Make finished
andriy/make_fate_x86 success Make fate finished

Commit Message

zhilizhao(赵志立) May 13, 2022, 9:40 a.m. UTC
has_b_frames should be output_reorder_delay field in AVS3 sequence
header and larger than 1. The parser implementation doesn't parse
that field. Decoder can set has_b_frames properly, so use FFMAX
here to avoid resetting has_b_frames from output_reorder_delay to 1.
---
 libavcodec/avs3_parser.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Andreas Rheinhardt May 13, 2022, 9:43 a.m. UTC | #1
Zhao Zhili:
> has_b_frames should be output_reorder_delay field in AVS3 sequence
> header and larger than 1. The parser implementation doesn't parse
> that field. Decoder can set has_b_frames properly, so use FFMAX
> here to avoid resetting has_b_frames from output_reorder_delay to 1.
> ---
>  libavcodec/avs3_parser.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/avs3_parser.c b/libavcodec/avs3_parser.c
> index d04d96a03a..0d2e940d1e 100644
> --- a/libavcodec/avs3_parser.c
> +++ b/libavcodec/avs3_parser.c
> @@ -114,7 +114,7 @@ static void parse_avs3_nal_units(AVCodecParserContext *s, const uint8_t *buf,
>              //            bitrate_high(12)
>              skip_bits(&gb, 32);
>  
> -            avctx->has_b_frames = !get_bits(&gb, 1);
> +            avctx->has_b_frames = FFMAX(avctx->has_b_frames, !get_bits(&gb, 1));
>  
>              avctx->framerate.num = avctx->time_base.den = ff_avs3_frame_rate_tab[ratecode].num;
>              avctx->framerate.den = avctx->time_base.num = ff_avs3_frame_rate_tab[ratecode].den;

FFMAX can evaluate its arguments more than once which is not intended here.

- Andreas
zhilizhao(赵志立) May 13, 2022, 10:15 a.m. UTC | #2
> On May 13, 2022, at 5:43 PM, Andreas Rheinhardt <andreas.rheinhardt@outlook.com> wrote:
> 
> Zhao Zhili:
>> has_b_frames should be output_reorder_delay field in AVS3 sequence
>> header and larger than 1. The parser implementation doesn't parse
>> that field. Decoder can set has_b_frames properly, so use FFMAX
>> here to avoid resetting has_b_frames from output_reorder_delay to 1.
>> ---
>> libavcodec/avs3_parser.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/libavcodec/avs3_parser.c b/libavcodec/avs3_parser.c
>> index d04d96a03a..0d2e940d1e 100644
>> --- a/libavcodec/avs3_parser.c
>> +++ b/libavcodec/avs3_parser.c
>> @@ -114,7 +114,7 @@ static void parse_avs3_nal_units(AVCodecParserContext *s, const uint8_t *buf,
>>             //            bitrate_high(12)
>>             skip_bits(&gb, 32);
>> 
>> -            avctx->has_b_frames = !get_bits(&gb, 1);
>> +            avctx->has_b_frames = FFMAX(avctx->has_b_frames, !get_bits(&gb, 1));
>> 
>>             avctx->framerate.num = avctx->time_base.den = ff_avs3_frame_rate_tab[ratecode].num;
>>             avctx->framerate.den = avctx->time_base.num = ff_avs3_frame_rate_tab[ratecode].den;
> 
> FFMAX can evaluate its arguments more than once which is not intended here.

Good catch, thanks! Here is v2:
http://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/296396.html

Use a variable low_delay to fix the FFMAX issue and serve as document.

> 
> - Andreas
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diff mbox series

Patch

diff --git a/libavcodec/avs3_parser.c b/libavcodec/avs3_parser.c
index d04d96a03a..0d2e940d1e 100644
--- a/libavcodec/avs3_parser.c
+++ b/libavcodec/avs3_parser.c
@@ -114,7 +114,7 @@  static void parse_avs3_nal_units(AVCodecParserContext *s, const uint8_t *buf,
             //            bitrate_high(12)
             skip_bits(&gb, 32);
 
-            avctx->has_b_frames = !get_bits(&gb, 1);
+            avctx->has_b_frames = FFMAX(avctx->has_b_frames, !get_bits(&gb, 1));
 
             avctx->framerate.num = avctx->time_base.den = ff_avs3_frame_rate_tab[ratecode].num;
             avctx->framerate.den = avctx->time_base.num = ff_avs3_frame_rate_tab[ratecode].den;