[FFmpeg-devel] [PATCH v2] avformat/mov: fix timecode with counter mode flag set

[Mark Reid]

On Sun, Jan 31, 2021 at 1:27 AM Mark Reid <mindmark at gmail.com> wrote:

>
>
> On Sat, Jan 16, 2021 at 5:48 PM <mindmark at gmail.com> wrote:
>
>> From: Mark Reid <mindmark at gmail.com>
>>
>> The current behaviour ends up squaring the avg_frame_rate if the conter
>> mode flag is set.
>> This messes up the timecode calculation, and looks to me as a regression
>> that
>> seems to have been introduced 428b4aac.
>>
>> Upon further testing is seems that no special case is need for having the
>> counter flag set.
>> av_timecode_init appears to handles the timecode correctly, at least in
>> the sample files
>> I have.
>>
>> Here is a sample mov file with the counter flag set
>> https://www.dropbox.com/s/5l4fucb9lhq523s/timecode_counter_mode.mov
>>
>> before the patch ffmpeg will report the timecode as:
>> 00:37:11:97 and warns that the timecode framerate is 576000000/1002001
>>
>> after patch:
>> 14:50:55:02
>>
>> ---
>>  libavformat/mov.c | 13 -------------
>>  1 file changed, 13 deletions(-)
>>
>> diff --git a/libavformat/mov.c b/libavformat/mov.c
>> index 3215b53636..f8856a43dd 100644
>> --- a/libavformat/mov.c
>> +++ b/libavformat/mov.c
>> @@ -2350,19 +2350,6 @@ FF_DISABLE_DEPRECATION_WARNINGS
>>              st->codec->time_base = av_inv_q(st->avg_frame_rate);
>>  FF_ENABLE_DEPRECATION_WARNINGS
>>  #endif
>> -            /* adjust for per frame dur in counter mode */
>> -            if (tmcd_ctx->tmcd_flags & 0x0008) {
>> -                int timescale = AV_RB32(st->codecpar->extradata + 8);
>> -                int framedur = AV_RB32(st->codecpar->extradata + 12);
>> -                st->avg_frame_rate.num *= timescale;
>> -                st->avg_frame_rate.den *= framedur;
>> -#if FF_API_LAVF_AVCTX
>> -FF_DISABLE_DEPRECATION_WARNINGS
>> -                st->codec->time_base.den *= timescale;
>> -                st->codec->time_base.num *= framedur;
>> -FF_ENABLE_DEPRECATION_WARNINGS
>> -#endif
>> -            }
>>              if (size > 30) {
>>                  uint32_t len = AV_RB32(st->codecpar->extradata + 18); /*
>> name atom length */
>>                  uint32_t format = AV_RB32(st->codecpar->extradata + 22);
>> --
>> 2.21.1 (Apple Git-122.3)
>>
>>
> Ping
>

ping