[FFmpeg-devel] [PATCH 1/2] avdevice/decklink: addition of copyts option

Carl Eugen Hoyos ceffmpeg at gmail.com
Sat Jan 20 22:10:31 EET 2018


2018-01-20 20:47 GMT+01:00 Marton Balint <cus at passwd.hu>:
>
> On Sat, 20 Jan 2018, Carl Eugen Hoyos wrote:
>
>> 2018-01-20 19:50 GMT+01:00 Marton Balint <cus at passwd.hu>:
>>>
>>> On Sat, 20 Jan 2018, Carl Eugen Hoyos wrote:
>>>
>>>> 2018-01-08 6:26 GMT+01:00  <vdixit at akamai.com>:
>>>>
>>>>> + at item decklink_copyts
>>>>> +If set to @option{true}, timestamps are forwarded as they are without
>>>>> removing
>>>>> +the initial offset.
>>>>> +Defaults to @option{false}.
>>>>
>>>> Why is the offset ever removed?
>>>> I believe this is not done for any other demuxer or is it?
>>>
>>> The code keeps track separate audio and video initial offset
>>
>> But they can't be independent or can they?
>> And if they can, how is A/V sync assured?
>
> Well, I am not entirely sure. Decklink has always had problems with
> timestamps and A-V desync was not uncommon when using the default clock
> sources. Probably a bug in the SDK.
>
> The whole offset removal is is originated from this commit:
>
> https://github.com/lu-zero/bmdtools/commit/b51ce3841ea763f27431ed9c77b99ae5404180c6

Thanks for the info, Carl Eugen


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