[FFmpeg-devel] [PATCH] avdevice/decklink: add option to drop frames till timecode is seen

[Ilinca Tudose]

My previous email was incorrect about "-wait_for_tc 1". The 2 commands used
were:

(1)
ffmpeg -loglevel trace  -timecode_format rp188any  -wait_for_tc 1 -f
decklink -probesize 15M -analyzeduration 5M -i "DeckLink Quad (1)" -t 30
-preset veryfast output.mov

(2)
ffmpeg -loglevel trace  -timecode_format rp188any  -wait_for_tc 1 -f
decklink -i "DeckLink Quad (1)" -t 30 -preset veryfast output.mov

The second command is the one that produced 1 frame offset in 3 of the
captures. The first command had 0 frames offset for all files tried.

On Wed, Nov 13, 2019 at 6:30 PM Ilinca Tudose <ilincat at google.com> wrote:

> Hi,
>
> We tested this with several types of tapes. The results are as follows:
>
> Out of 58 captures on Betacam tapes 55 had 0 frame offset and 3 had an
> offset of 1 frame. All 3 were captured using the flag "-wait_for_tc 1".
> Out of the 58 captures roughly half were captured with and half without "-wait_for_tc
> 1".
>
> Out of 26 HDCAM captures (50/50 with/without "-wait_for_tc 1") all 26 had
> 0 TC offset.
>
> Let me know if there's any questions re testing. The testing setup is the
> same as previously mentioned.
>
> Thanks,
> ilinca
>
> On Wed, Nov 13, 2019 at 5:40 PM Gyan <ffmpeg at gyani.pro> wrote:
>
>> As suggested in the review of an earlier patch*, this one drops frames
>> till a TC is seen.
>>
>> Testing results to follow.
>>
>> Thanks,
>> Gyan
>>
>> *https://patchwork.ffmpeg.org/patch/14081/
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>
>
>
>

-- 

---
Ilinca Tudose | Technical Solutions Consultant, Digitization Operations |
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