[FFmpeg-cvslog] VC1testenc: convert pts values to correct time-base.

[Baptiste Coudurier]

On 1/29/11 4:08 AM, Reimar D?ffinger wrote:
> On Sat, Jan 29, 2011 at 01:05:36PM +0100, Reimar D?ffinger wrote:
>> On Sat, Jan 29, 2011 at 03:47:49AM -0800, Baptiste Coudurier wrote:
>>> On 1/29/11 3:01 AM, Reimar D?ffinger wrote:
>>>> ffmpeg | branch: master | Reimar D?ffinger <Reimar.Doeffinger at gmx.de> | Sat Jan 29 11:56:25 2011 +0100| [76c802e989b61423c1554cf204f96f70b3edb145] | committer: Reimar D?ffinger
>>>>
>>>> VC1testenc: convert pts values to correct time-base.
>>>>
>>>> VC1 test container always uses time-base 1 ms, so we must convert
>>>> from whatever time-base the application gave us to that, otherwise
>>>> the video will play at ridiculous speeds.
>>>> It would be possible to signal that a container supports only one
>>>> time-base and have code in a layer above do the conversion, but
>>>> for a single format this seems over-engineered.
>>>>
>>>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=76c802e989b61423c1554cf204f96f70b3edb145
>>>> ---
>>>>
>>>>  libavformat/vc1testenc.c |    5 ++++-
>>>>  1 files changed, 4 insertions(+), 1 deletions(-)
>>>>
>>>> diff --git a/libavformat/vc1testenc.c b/libavformat/vc1testenc.c
>>>> index 507b332..06431da 100644
>>>> --- a/libavformat/vc1testenc.c
>>>> +++ b/libavformat/vc1testenc.c
>>>> @@ -55,11 +55,14 @@ static int vc1test_write_packet(AVFormatContext *s, AVPacket *pkt)
>>>>  {
>>>>      RCVContext *ctx = s->priv_data;
>>>>      ByteIOContext *pb = s->pb;
>>>> +    uint32_t pts = av_rescale(pkt->pts,
>>>> +                              1000 * (uint64_t)s->streams[0]->time_base.num,
>>>> +                              s->streams[0]->time_base.den);
>>>
>>> This should not be needed if av_set_pts_info is correctly used in
>>> write_header.
>>
>> That means that an application must re-check the time-base after
>> av_write_header, that is definitely _not_ documented, or am I
>> missing something?
> 
> And I forgot to say that this just pushes the need for conversion
> onto the libavformat user, I am not exactly fond of that.

This is how it works currently, and since a long time.

The user specify the time base using codec->time_base, and the container
uses it.

Some containers only support one time base (mpeg ps/ts for example
1/90000), so they can't use the one specified.

If you have timestamps problems, something is wrong somewhere else, but
this hunk should not needed, no muxer do this currently.

-- 
Baptiste COUDURIER
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
FFmpeg maintainer                                  http://www.ffmpeg.org