[Libav-user] creating a basic live transcoder

[Luis Felipe Domínguez Vega]

Paul I agree with you, but the thing is that i dont found a good example 
or explain about how to get that working, even to set the DTS. Can you 
give to me a resource?

On 1/2/23 18:01, Paul B Mahol wrote:
>
>
> On Mon, Jan 2, 2023 at 9:48 PM Luis Felipe Domínguez Vega via 
> Libav-user <libav-user at ffmpeg.org> wrote:
>
>     Found the best documentation about ffmpeg outside ffmpeg.
>
>     https://github.com/leandromoreira/ffmpeg-libav-tutorial#chapter-1---syncing-audio-and-video
>
>     There is well explained the PTS definition very very well. Used the
>     calculations from that readme and set this:
>
>     ```
>              packet->pts = dvCodecCtx->time_base.den /
>     av_q2d(dvCodecCtx->framerate) *  frameCounter++;
>
>     ```
>
>     Now the input stream can restart, get wrong PTS, TS, whatever that
>     dont
>     broke my output stream timing.
>
>
> Technically speaking that line is pure hack as it does use double 
> floating point precision for calculations when it is not really needed 
> to use and may after some relative long time give bad results.
>
>
>     On 1/2/23 16:39, Luis Felipe Domínguez Vega via Libav-user wrote:
>     > Hi, I'm trying to create in C a basic live transcoder that use my
>     > NVidia for hardware transcoding. I trying to set the decoded
>     frame PTS
>     > to my own because the source of the video is a UDP stream and
>     can be
>     > restarted. So i want manage by myself the PTS value to avoid a
>     restart
>     > of that value.
>     >
>     > Really i dont found a good documentation about to how manage and
>     > create from 0 that PTS value.
>     >
>     > Right now iw geting the frame from decoder, "modify ->pts", and
>     send
>     > to encoder, only for testing i get a variable with "frame" counter
>     > that start at 0, tested this:
>     >
>     > ```
>     > frame->pts = frameCounter++
>     > ```
>     >
>     > Of course this, after video encoder completed, drop so many
>     frames on
>     > the player (codec is h264 at input and output). So i think that
>     i dont
>     > geting the idea behind pts.
>     >
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