[Libav-user] AVPacket to GStreamer pipeline

[Việt Hùng Nguyễn]

It seems before send to gstreamer, you need de-packetize first, this why
you demux by libav to AVFrame, it de-packetize the stream to complete data
of frame, then it works with GStreamer.

On Mon, 4 Jan 2021 at 17:45 fre deric <frenky.picasso at seznam.cz> wrote:

> My goal is to demux video stream in libav and then decode it in GStreamer
> pipeline.
>
> My approach is to take AVPacket from the video stream in the first thread
> and send it to GStreamer pipeline in the second thread. Important parts of
> code are here:
>
> // -- THREAD 1 --
> // Take data from AVPacket
> img_data = (guchar *)packet.data;
> size = packet.size;
> // Create GStreamer buffer
> buffer = gst_buffer_new_allocate(NULL, size, NULL);
> gst_buffer_map(buffer, &map, GST_MAP_WRITE);
> memcpy((guchar *)map.data, img_data, gst_buffer_get_size(buffer));
> map.size = size;
> gst_buffer_unmap(buffer, &map);
> // Send the buffer to appsrc element in the pipeline.
> gstret = gst_app_src_push_buffer((GstAppSrc *)app_source, buffer);
>
> // -- THREAD 2 --
> // A video cap for appsrc element
> const gchar *video_caps = "video/x-theora, width=1920, height=1080,
> framerate=30/1";
> // GStreamer pipeline
> string = g_strdup_printf("appsrc name=testsource caps=\"%s\" ! theoradec !
> videoconvert ! autovideosink", video_caps);
>
> However, I am getting following error in GStreamer pipeline:
> "
> ERROR from element theoradec0: Could not decode stream.
> Debugging info: gsttheoradec.c(812): theora_handle_data_packet ():
> /GstPipeline:pipeline0/GstTheoraDec:theoradec0: no header sent yet
> "
>
> I also tested a version, when the AVPacket was decoded to AVFrame by libav
> and then sent to the gstreamer pipeline and it WORKS:
>
> -- THREAD 1 --
> // Decode.
> avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
> // Take data from AVFrame
> img_data = (guchar *)pFrame->data
> size = av_image_get_buffer_size(AV_PIX_FMT_BGR24, 1920, 1080, 1);
> // same way as before.
>
> -- THREAD 2 --
> const gchar *video_caps = "video/x-raw, format=BGR, width=1920,
> height=1080,
> framerate=30/1";
> string = g_strdup_printf("appsrc name=testsource caps=\"%s\" ! videoconvert
> ! autovideosink", video_caps);
>
>
> All this is tested on this video file:
> container: ogg
> codec: Theora
> dim: 1920x1080
> framerate: 30fps
>
>
> Why does sending the AVFrame to GStreamer pipeline work, but not the
> AVPacket?
>
>
>
> --
> Sent from: http://libav-users.943685.n4.nabble.com/
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