I don't know if this is right but this is how I rescale timestamps:
//Back to yuv for encoding flattened image
yuv_pix->av_frame=RGBtoYUV(rgb_pix->av_frame, in_stream->codec);
avcodec_encode_video2(out_stream->codec, &styl_pkt,
yuv_pix->av_frame, &got_something);
if(!got_something)
{
INFO(stderr, ":-( Unable to encode yuv frame.\n");
exit(0);
}
//convert timestamps from in time_base to out time_base
av_packet_rescale_ts(&styl_pkt, in_stream->time_base,
out_stream->time_base);
//log_packet(in_video_ctx->format_ctx, &orig_pkt, "Video orig.
pkt");
//log_packet(out_video_ctx->format_ctx, &styl_pkt, "Video styl.
pkt");
ret = av_write_frame(out_video_ctx->format_ctx, &styl_pkt);
if (ret < 0)
{
INFO(stderr, "Error muxing packet\n");
break;
}
I'm sure I'm wrong somewhere with this timestamps management but I can't figure
out how.
Thanks again if you can help me further!
Le 3 sept. 2015 à 18:23, Robert Krüger <[email protected]> a écrit :
>
>
> On Thu, Sep 3, 2015 at 5:41 PM, Talgorn François-Xavier
> <[email protected]> wrote:
> Hi Krueger,
>
> Thanks for your reply.
> I did check the timestamps and durations of packets.
> It appears that respectives timestamps (original/encoded) are in different
> formats but consistent (incremental).
> I set the timebase for encoded file to the same as the original
> (in_ctx->format_ctx is the original context).
>
> o_codec_ctx->time_base.num =
> in_ctx->format_ctx->streams[in_ctx->video_stream_idx]->codec->time_base;
> o_codec_ctx->time_base.den =
> in_ctx->format_ctx->streams[in_ctx->video_stream_idx]->codec->time_base;
>
> I don't know if this is OK to duplicate a timebase from H264 to be used in a
> MP4 context.
> Since it defines the frame rate only (not the ticks/frame) it should OK I
> guess.
>
> no, it does not. mov/mp4 don't have a concept like frame rate.
>
> The encoder gives you packets that have timestamps that are based on what you
> gave the encoder as timebase. The muxer has the freedom to change that
> timebase in avformat_write_header and if it does, the packets you get from
> the encoder have incorrect timestamps, if you don't rescale them to the
> timebase of the AVStream modified by the muxer. Check the example muxing.c in
> the docs. You have to do what's done there (see line 83). If you don't, what
> you describe (incorrect frame rate) may very well be the result.
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