[Libav-user] PTS values and writing encoded audio and video frames ?

NITIN GOYAL nitinkumgoyal at gmail.com
Thu Apr 12 09:06:19 CEST 2012


I think it is always not necessary have to both audio and video with same
size. I have seen the videos which are greater in length that audio and
there was silence at the end of the video.  If there is no silence in the
end of your video then you need to track the PTS values of the audio
and check where it got shortened.


On Thu, Apr 12, 2012 at 12:28 PM, ashika umanga <umanga.forums at gmail.com>wrote:

> I mean, I used "muxing.c" to generate the OGG file.That means both audio
> and video stream should have the same length,isnt it ?
>
>
>
> On Thu, Apr 12, 2012 at 3:31 PM, Gagandeep Bawa <
> gagandeep.bawa at ironroad.com> wrote:
>
>> You have to check your video frame rate. I worked on IPhone recorded
>> videos files and it varies between 15 to 30.
>>
>>
>> On Thu, Apr 12, 2012 at 11:58 AM, ashika umanga <umanga.forums at gmail.com>wrote:
>>
>>> When I encode an OGG file with Theora+Speex , my video length is longer
>>> than the audio playback.
>>> Anytips on this ?
>>>
>>> On Thu, Apr 12, 2012 at 2:51 PM, Gagandeep Bawa <
>>> gagandeep.bawa at ironroad.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> These PTS and DTS used for sync between audio and video data while
>>>> encoding and presentation. Check below link for more details.
>>>>
>>>> *http://dranger.com/ffmpeg/tutorial05.html*
>>>>
>>>> Thanks,
>>>> Gagan
>>>>
>>>> On Thu, Apr 12, 2012 at 11:14 AM, ashika umanga <
>>>> umanga.forums at gmail.com> wrote:
>>>>
>>>>> Greetings all,
>>>>>
>>>>> I am writing a wrapper class for video/audio encoding by following the
>>>>> "muxing.c".
>>>>> http://ffmpeg.org/doxygen/trunk/muxing_8c-source.html
>>>>>
>>>>> I see in the example that before writing frames to the file ,is checks
>>>>> whether the PTS value of audiostream is
>>>>> lesser than that of videostream.
>>>>>
>>>>> code snippet:
>>>>>
>>>>>  if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
>>>>>             write_audio_frame(oc, audio_st);
>>>>>         } else {
>>>>>             write_video_frame(oc, video_st);
>>>>>             picture->pts++;
>>>>>         }
>>>>>
>>>>> Can someone explain why this test is done? Whats the connection
>>>>> between PTS values ?
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Libav-user mailing list
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>>>>>
>>>>>
>>>>
>>>>
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>>
>>
>> --
>>
>> Thanks & Regards,
>> Gagandeep, Tech Lead Mobility
>>
>> +91- 7307470044
>>
>>
>> -------------------------------------------------------------------------------
>>
>> Ironroad IT India Pvt. Ltd.
>>
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>
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