Questions about transcoding video with audio and subtitle passthrough using MKV files

Toby Widdows toby at rosecott.net
Fri Mar 5 20:05:25 UTC 2021


Hi,

so i've been fiddling and can get the audio streams to pass through if i know what they are eg 

gst-launch-1.0 filesrc location=2.mkv ! matroskademux name=demux demux.video_0 ! queue ! h264parse ! nvv4l2decoder ! nvv4l2h265enc bitrate=2000000 ! h265parse ! matroskamux name=mux ! progressreport update-freq=1 ! filesink location=2222.mkv demux.audio_0 ! queue ! aacparse !  mux.

this works and will parse the AAC audio track through the output with no apparent loss in performance

I got this from the Nvidia forum for gstreamer and it does the same thing but does not need to know what the audio stream is

gst-launch-1.0 filesrc location=2.mkv ! matroskademux name=demux demux.video_0 ! queue ! video/x-h264 ! h264parse ! nvv4l2decoder ! nvv4l2h265enc bitrate=20000000 ! h265parse ! queue ! mux.video_0 demux.audio_0 ! queue ! mux.audio_0 matroskamux name=mux ! progressreport update-freq=1 ! filesink location=2222.mkv

I can see there are differences but because i cant understand the command structure, and it appears to be very flexible, i cant make the top work using the bottom one commands.  everything is in a different order! and to my poor brain that just seems wrong!

TIA Toby


------ Original Message ------
From: "gotsring" <gotsring at live.com>
To: gstreamer-devel at lists.freedesktop.org
Sent: 05/03/2021 17:32:08
Subject: Re: Questions about transcoding video with audio and subtitle passthrough using MKV files

Yep. Though I would expected that you probably have to replace it with an
audio parser that matches your audio streams.
 
You'll have to experiment with this. You can test the outputs with
gst-play-1.0. I think pressing 'a' or 's' in the output window switches
between the audio and subtitle streams, so you can verify that they're all
there.
 
 
 
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