[Ffmpeg-devel] Frame rates and time_base

Bill May wmay
Sat May 7 00:20:18 CEST 2005



M?ns Rullg?rd wrote:
> If PTS and DTS are different for an encoded frame, there is no way to
> determine one from the other.  While decoding a sequence of frames, it
> is of course possible to determine any PTS, given the PTS of one of
> the frames.

Absolutely.

Is there an API in ffmpeg that will do this ?  (It can get quite
complicated for H.264 and re-ordered P frames).

> 
> While encoding, only PTS is meaningful as input, and the encoder may
> reorder the output, resulting in different values for PTS and DTS of
> the encoded frame.

I understand this, and I apologize if I did not make myself clear; is it
possible using the existing APIs to get the PTS value of the encoded
frame that is being returned (ie: after it is reordered) ?

For example, in x264, for x264_encoder_encode, you set pic_in.i_pts to the
timestamp of the frame to encode.

pic_out.i_pts will be set to the correct PTS when there is a frame to output.

Is there a similiar function in ffmpeg ?

Thanks,
Bill





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