On 26.10.19 14:37, Carl Eugen Hoyos wrote:
Am Sa., 26. Okt. 2019 um 14:14 Uhr schrieb Ingmar Rieger <d...@irieger.net>:
On 26.10.19 10:59, Carl Eugen Hoyos wrote:
That's at least a surprising argumentation given the number of encoders
included in FFmpeg.
Did I miss something? For me the relevant codecs I know for intermediate
work are ProRes, DNxHR and Cineform with the later being seldomly used
but the only open standard and as I recently found out supported in
Resolve for some time now so as my main target is Resolve it seems worth
giving it a try. ProRes and DNxHR are both proprietary with only reverse
engineered codecs available.
Correct:
FFmpeg contains encoders for both ProRes and DNxHR.
(Note that Cineform being an open standard is a joke, it is exactly as
proprietary as the others.)
[...]
Ok you are right. But still Apple is evil etc. (Blackmagic accidentially
activated ProRes in a beta version showing everyone what is already
known: There is quicktime support ready...)
Still this discussion helps nothing regarding writing the correct
container metadata.
So basically I have an input like frame_rate (in integer for simplicity,
don't care about the crazy 23.98 and other strange rates), a frame
number from 0 to NUM_FRAMES-1 and ideally a start time input -> How to
set the correct time base/rates and calculate the frame dts/pts?
As said, you cannot set the time base (you can but you don't have to) but
you have to read the time base used by the muxer, then calculate timestamps
using this time base, should be possible with av_rescale_q().
Ok, so what do I set and what will be set automatically in general?
As I said I found no documentation describing how to setup a stream
manually, that is why I asked in the first place. Just used the remux
example (which uses avcodec_parameters_copy) as the base and manually
read information from an existing Cineform encoded by Blackmagic to set
the parameters manually.
With
> out_avstream->avg_frame_rate = (AVRational){24, 1};
> out_avstream->r_frame_rate = out_avstream->avg_frame_rate;
I now have to correct frame rate shown when av_dump_format is called but
after writing some frames the frame rate seems to be reset.
My current code that tries to set correct pts/dts values:
> AVRational timebase_clip = out_avstream->time_base;
> AVRational timebase_count = (AVRational){1, 24}; // also tried {24, 1}
> pkg.pts = av_rescale_q(frame, timebase_count, timebase_clip);
> pkg.dts = pkg.dts;
This results in errors displayed by libav:
> [mov @ 0x55b6572cfbc0] Application provided invalid, non
monotonically increasing dts to muxer in stream 0: 6 >= 6
So what is the right way to go from frame number to correct timebase
conversion. Can someone just give a hint how to correctly call this
conversions?
From the outputs and everything I would say I seem to be near a solution.
--
Kind regards,
Ingmar
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