How to use gstreamer for transcoding and resizing from mp4(h264/aac) to mp4(h264/mp3)?

Question

I want to transcode and resize mp4.(mp4-h264_1920x1080/aac => mp4-h264_640x480/mp3) using gstreamer. I wrote down this command.

$ gst-launch-0.10 filesrc location=./gain_1.mp4 ! qtdemux name=demux demux.video_00 ! queue ! ffdec_h264 ! videoscale ! 'video/x-raw-yuv,width=640,height=480' ! x264enc ! queue ! qtmux name=mux mux.video_0 demux.audio_00 ! queue ! ffdec_aac ! lame bitrate=128 ! queue ! mux.audio_0 mux. ! filesink location=0000.mp4 –v -e
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
Redistribute latency...
^CCaught interrupt -- handling interrupt.
Interrupt: Stopping pipeline ...

(gst-launch-0.10:17958): GLib-CRITICAL **: Source ID 1 was not found when attempting to remove it
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
Freeing pipeline ...

which didn't work.

Transcoding video-only works :

gst-launch-0.10 filesrc location=./gain_1.mp4 ! qtdemux name=demux demux.video_00 ! queue ! ffdec_h264 ! videoscale ! 'video/x-raw-yuv, width=640, height=480' ! x264enc ! queue ! mux. mp4mux name=mux ! filesink location=0000.mp4 –v -e

And transcoding audio-only too:

gst-launch-0.10 filesrc location=./gain_1.mp4 ! qtdemux name=demux demux.audio_00 ! ffdec_aac ! lame bitrate=128 ! queue ! mux. mp4mux name=mux ! filesink location=0000.mp4 –v -e

How can I transcode audio and video with the same command?

Answer 1

@Lionel.J I would like to suggest two improvements:

1. if possible, use gstreamer-1
2. your solution reads the source file twice. That's not necessary. Furthermore, the audio and video streams are not synchronized when you do this. You can read both audio and video streams out of qtdemux.

This is a pipeline which does the job with gstreamer-1 and reads the source only once:

gst-launch-1.0 -e filesrc location=/path/to/big_buck_bunny_720p_h264.mov ! \
decodebin name=decode ! \
videoscale ! 'video/x-raw,width=640,height=480' ! \
x264enc ! queue ! mp4mux name=mp4mux ! filesink location=0000.mp4 \
decode. ! audioconvert ! lamemp3enc bitrate=128 ! queue ! mp4mux.