[FFmpeg-devel] [PATCH] lavd/lavfi.c: Set time_base for 608 cc to container time_base.

[Thilo Borgmann]

Am 16.07.21 um 09:45 schrieb Thilo Borgmann:
> Hi,
> 
>>>> when transcoding 608 cc, the cc stream frame pts is set to the same value as its container frame's pts. However, the time_base is always set to 1/90000 (default) in the initialization stage. Which causes timing issues when the container time_base is actually not 1/90000.
>>>
>>> identical v2 attached that also includes updates to the FATE references affected by the patch (and failed with patchwork of course).
>>>
>>> -Thilo
>>>
>>> From 41b619e5d5083ca59a41cca9cb515190939d6573 Mon Sep 17 00:00:00 2001
>>> From: Yun Zhang <yunz at devvm259.frc1.facebook.com>
>>> Date: Mon, 28 Jun 2021 15:09:42 +0200
>>> Subject: [PATCH] lavd/lavfi.c: Set time_base for 608 cc to container
>>>  time_base.
>>>
>>> Suggested-By: ffmpeg at fb.com
>>> ---
>>>  libavdevice/lavfi.c            |  3 +++
>>>  tests/ref/fate/sub-cc          |  4 ++--
>>>  tests/ref/fate/sub-cc-realtime | 38 +++++++---------------------------
>>>  3 files changed, 13 insertions(+), 32 deletions(-)
>>>
>>> diff --git a/libavdevice/lavfi.c b/libavdevice/lavfi.c
>>> index 57d977e7ce..e07f20c872 100644
>>> --- a/libavdevice/lavfi.c
>>> +++ b/libavdevice/lavfi.c
>>> @@ -100,6 +100,7 @@ static int create_subcc_streams(AVFormatContext *avctx)
>>>      LavfiContext *lavfi = avctx->priv_data;
>>>      AVStream *st;
>>>      int stream_idx, sink_idx;
>>> +    AVRational *time_base;
>>>  
>>>      for (stream_idx = 0; stream_idx < lavfi->nb_sinks; stream_idx++) {
>>>          sink_idx = lavfi->stream_sink_map[stream_idx];
>>> @@ -109,6 +110,8 @@ static int create_subcc_streams(AVFormatContext *avctx)
>>>                  return AVERROR(ENOMEM);
>>>              st->codecpar->codec_id = AV_CODEC_ID_EIA_608;
>>>              st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
>>> +            time_base = &avctx->streams[stream_idx]->time_base;
>>> +            avpriv_set_pts_info(st, 64, time_base->num, time_base->den);
>>
>> This look like an unnecessariily complicated way to write
>> st->time_base.{num,den}
> 
> Changed patch attached.

Will push soon (tm) if there are no further comments.

Thanks,
Thilo