Re: [FFmpeg-devel] [PATCH] avformat/mov: correct 0 valued entries in stts

["\"zhilizhao(赵志立)\"" <quinkblack@foxmail.com>]

> On Dec 27, 2021, at 2:38 PM, zhilizhao(赵志立) <quinkblack@foxmail.com> wrote:
> 
>> On Dec 27, 2021, at 1:57 PM, Gyan Doshi <ffmpeg@gyani.pro> wrote:
>> 
>> As per ISO 14496-12, sample duration of 0 is invalid except for
>> the last entry.
>> 
>> In addition, also catch 0 value for sample count.
>> ---
>> libavformat/mov.c | 12 ++++++++++++
>> 1 file changed, 12 insertions(+)
>> 
>> diff --git a/libavformat/mov.c b/libavformat/mov.c
>> index 2aed6e80ef..fb7406cdd6 100644
>> --- a/libavformat/mov.c
>> +++ b/libavformat/mov.c
>> @@ -2968,6 +2968,18 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>>        av_log(c->fc, AV_LOG_TRACE, "sample_count=%d, sample_duration=%d\n",
>>                sample_count, sample_duration);
>> 
>> +        if (!sample_count) {
>> +        av_log(c->fc, AV_LOG_WARNING, "invalid sample count of 0 in stts for st %d at entry %u; changing to 1.\n",
>> +               c->fc->nb_streams-1, i);
> 
> No, zero is a valid value, for example, fragmented mp4.

Ok, it’s sample_count, not entry_count.

> 
>> +        sc->stts_data[i].count = sample_count = 1;
>> +        }
>> +
>> +        if (!sample_duration && i != entries-1) {
>> +        av_log(c->fc, AV_LOG_WARNING, "invalid sample delta of 0 in stts for st %d at entry %u; changing to 1.\n",
>> +               c->fc->nb_streams-1, i);
>> +        sc->stts_data[i].duration = sample_duration = 1;
>> +        }
>> +
>>        duration+=(int64_t)sample_duration*(uint64_t)sample_count;
>>        total_sample_count+=sample_count;
>>    }
>> -- 
>> 2.33.0
>> 
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