[FFmpeg-devel] [PATCH v2] avformat/segment: calculate segment durations correctly.

[Gyan Doshi]

On 2023-01-12 11:29 am, Gyan Doshi wrote:
>
>
> On 2023-01-07 05:37 pm, Gyan Doshi wrote:
>> segment_time and segment_times are defined as duration 
>> specifications, not
>> timestamps, so calculation of segment duration must account for initial
>> timestamp. Fixed.
>>
>> FATE ref for segment-mp4-to-ts changed on account of avoiding premature
>> segment cut at the end of the first segment.
>
> Comments?

Plan to push tomorrow.

>
>> ---
>>   libavformat/segment.c            | 15 +++++++++++++++
>>   tests/ref/fate/segment-mp4-to-ts |  4 ++--
>>   2 files changed, 17 insertions(+), 2 deletions(-)
>>
>> diff --git a/libavformat/segment.c b/libavformat/segment.c
>> index 0e6421ea5d..80e4bf851c 100644
>> --- a/libavformat/segment.c
>> +++ b/libavformat/segment.c
>> @@ -116,6 +116,7 @@ typedef struct SegmentContext {
>>       int64_t initial_offset;    ///< initial timestamps offset, 
>> expressed in microseconds
>>       char *reference_stream_specifier; ///< reference stream specifier
>>       int   reference_stream_index;
>> +    int64_t reference_stream_first_pts;    ///< initial timestamp, 
>> expressed in microseconds
>>       int   break_non_keyframes;
>>       int   write_empty;
>>   @@ -746,6 +747,8 @@ static int seg_init(AVFormatContext *s)
>>              seg->reference_stream_index,
>> av_get_media_type_string(s->streams[seg->reference_stream_index]->codecpar->codec_type));
>>   +    seg->reference_stream_first_pts = AV_NOPTS_VALUE;
>> +
>>       seg->oformat = av_guess_format(seg->format, s->url, NULL);
>>         if (!seg->oformat)
>> @@ -898,6 +901,18 @@ calc_times:
>>               pkt->flags & AV_PKT_FLAG_KEY,
>>               pkt->stream_index == seg->reference_stream_index ? 
>> seg->frame_count : -1);
>>   +    if (seg->reference_stream_first_pts == AV_NOPTS_VALUE &&
>> +        pkt->stream_index == seg->reference_stream_index &&
>> +        pkt->pts != AV_NOPTS_VALUE) {
>> +        seg->reference_stream_first_pts = av_rescale_q(pkt->pts, 
>> st->time_base, AV_TIME_BASE_Q);
>> +    }
>> +
>> +    if (seg->reference_stream_first_pts != AV_NOPTS_VALUE) {
>> +        end_pts += (INT64_MAX - end_pts >= 
>> seg->reference_stream_first_pts) ?
>> +                    seg->reference_stream_first_pts :
>> +                    INT64_MAX - end_pts;
>> +    }
>> +
>>       if (pkt->pts != AV_NOPTS_VALUE)
>>           pkt_pts_avtb = av_rescale_q(pkt->pts, st->time_base, 
>> AV_TIME_BASE_Q);
>>   diff --git a/tests/ref/fate/segment-mp4-to-ts 
>> b/tests/ref/fate/segment-mp4-to-ts
>> index 54fcadb846..2994416270 100644
>> --- a/tests/ref/fate/segment-mp4-to-ts
>> +++ b/tests/ref/fate/segment-mp4-to-ts
>> @@ -23,7 +23,7 @@
>>   0,      50400,      54000,     3600,      607, 0xc53c2339, F=0x0, 
>> S=1,        1
>>   0,      54000,      72000,     3600,     4755, 0x2f642b58, F=0x0, 
>> S=1,        1
>>   0,      57600,      64800,     3600,     1182, 0xbe1a4847, F=0x0, 
>> S=1,        1
>> -0,      61200,      61200,     3600,      809, 0x8d948a4e, F=0x2, 
>> S=1,        1
>> +0,      61200,      61200,     3600,      809, 0x8d948a4e, F=0x0, 
>> S=1,        1
>>   0,      64800,      68400,     3600,      656, 0x4fa03c2b, F=0x0, 
>> S=1,        1
>>   0,      68400,      86400,     3600,    26555, 0x5629b584, 
>> S=1,        1
>>   0,      72000,      79200,     3600,     1141, 0x761b31e8, F=0x0, 
>> S=1,        1
>> @@ -71,7 +71,7 @@
>>   0,     223200,     226800,     3600,      809, 0x84e37fee, F=0x0, 
>> S=1,        1
>>   0,     226800,     244800,     3600,     4541, 0xd4e5c0de, F=0x0, 
>> S=1,        1
>>   0,     230400,     237600,     3600,     1545, 0x0099fc98, F=0x0, 
>> S=1,        1
>> -0,     234000,     234000,     3600,      929, 0xfd72d049, F=0x0, 
>> S=1,        1
>> +0,     234000,     234000,     3600,      929, 0xfd72d049, F=0x2, 
>> S=1,        1
>>   0,     237600,     241200,     3600,      829, 0xcfda9e96, F=0x0, 
>> S=1,        1
>>   0,     241200,     259200,     3600,    24220, 0x5ca21d71, 
>> S=1,        1
>>   0,     244800,     252000,     3600,     1422, 0xcde6cc34, F=0x0, 
>> S=1,        1
>
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