[Kdenlive-devel] [Kdenlive] Camcorder footage Panasonic HDC-SD9
schreter at gmx.net
Wed Jan 14 20:50:51 UTC 2009
I've tried -vsync 0 with vanilla ffmpeg. No, it's not the same. It
dumps an error:
Error, Invalid timestamp=15, last=17
I suppose the camcorder misses some frames when encoding starts, which
requires ffmpeg to introduce some duplicates. It seems like the frames
come in "interesting" order in the AVCHD file and somehow ffmpeg as well
as mlt are not able to reorder them correctly (e.g., because they do not
keep enough previous frames in the buffer?).
@Dan: I looked at the source in producer_avformat.c in MLT. I don't
believe this is the problem. It's more like ffmpeg's libavformat is not
producing correct timestamps and therefore I will look there (dts/pts
computation in utils.c/av_read_frame*, I suppose). This would also
explain why ffmpeg itself is producing jerky videos (without my patch).
Correcting it will most probably also correct kdenlive support for this
As I said, on weekend I plan to look at it in some more detail.
Jean-Michel Pouré wrote:
> On Tue, 2009-01-13 at 21:06 +0100, Ivan Schreter wrote:
>> Regarding the ffmpeg patch, as I wrote, this is NO SOLUTION. It's just
>> workaround for this specific camcorder AVCHD format. It might cause
>> unpredictable results on other source material. But I didn't post it
>> anywhere else yet and don't have much time right now to do it. If you
>> wish, feel free to discuss it with ffmpeg developers and put me on
>> CC :-)
>> BTW, do you know by chance where is the video timing (or computation
>> timestamps for timestamp-less frames) handled in kdenlive? Maybe I
>> look at it during the weekend and eventually make a workaround
>> in kdenlive.
> Dear Ivan,
> I answer you on Kdenlive mailing list. This is about your workaround:
> I proposed the solution on FFmpeg mailing list and someone answered me
> that this was the same as -vsync 0 FFmpeg option. I don't understand
> what video sync to zero means. But then how is the video synced? Maybe
> you can explain us ...
> Kind regards,
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