[FFmpeg-devel] [PATCH] avdevice/decklink: adjust for timecode lag

[Gyan]

On 17-08-2019 08:42 PM, Marton Balint wrote:
>
>
> On Wed, 14 Aug 2019, Marton Balint wrote:
>
>>
>>
>> On Wed, 14 Aug 2019, Gyan wrote:
>>
>>>
>>>
>>> On 09-08-2019 04:59 PM, Ilinca Tudose wrote:
>>>> Hi Marton,
>>>>
>>>> The issue with the out of sync TC was reproducible on all tapes and 
>>>> decks
>>>> that we tested. I don't have the exact number now, but a few 
>>>> dozens, less
>>>> than 100. They all had between 7 and 17 frames out of sync. We were 
>>>> not
>>>> able to obtain anything more in sync than 7 frames.
>>>>
>>>> The TC sync was tested by setting up the deck to "burn" the TC with 
>>>> the
>>>> image while capturing the content with TC through ffmpeg. We then 
>>>> play the
>>>> file in a player that supports timecodes and compare the burned-in 
>>>> TC with
>>>> the one captured in the metadata.
>>>>
>>>> We used Decklink quad 2 and several Sony decks: J30, J3, JH3. We 
>>>> tested on
>>>> multiple decks from each model and confirmed the issue was present 
>>>> + that
>>>> Gyan's patch seemed to fix it. We have used several types of 
>>>> Betacam tapes
>>>> and HDCAM tapes. I can not comment on whether this is the best 
>>>> solution,
>>>> but can confirm it works.
>>>>
>>>> Let me know if you need more info.
>>>>
>>>> Thanks,
>>>> ilinca
>>>
>>> Ping.
>>
>> Sorry, I need a bit more time to investigate.
>
> OK, I did a couple of tests myself for HD and SD pal signals, and it 
> seems to me if signal autodetection is used, so no format_code is 
> specified then timecode is readily available in the first frame. I was 
> using BlackMagic SDK 11.1 for testing by the way. Can you confirm the 
> same behaviour with your setup?

So, were you able to reproduce the issue _with_  format_code specified?

Gyan