how to use avdec_g726 to decode g726 raw data

[Nicolas Dufresne]

Le jeudi 11 mars 2021 à 12:10 +0800, strong a écrit :
> hi, all
>     I want to use gstreamer/libav to encode$decode with g726, the command line
> I used is
> encode:
> gst-launch-1.0 alsasrc device=hw:0 ! audio/x-raw, rate=8000, channels=1, format=S16LE, layout=interleaved ! avenc_g726 code_size=5 ! filesink location=test.g726
> it can work well, I can use ffplay to decode test.g726
> 
> decode:
> gst-launch-1.0 filesrc location=test.g726 blocksize=100 ! audio/x-adpcm,
> bitrate=40000, rate=8000, channels=1, layout=g726 ! avdec_g726 ! filesink
> location=test.pcm
> 
> location=test.pcm

Took me a bit of research, but found this:

0:00:00.343734425 725274 0x55c94b173000 DEBUG           audiodecoder gstaudiodecoder.c:2396:gst_audio_decoder_sink_eventfunc:<avdec_g726-0> unsupported format; ignoring

Didn't search further, but the decoder refuses byte segments and fails everything. You can hack/workaround that with filesrc do-timestamp=TRUE.

gst-launch-1.0 filesrc do-timestamp=TRUE location=test.g726 blocksize=100 ! audio/x-adpcm,bitrate=40000, rate=8000, channels=1, layout=g726 ! avdec_g726 ! filesink location=test.pcm

Would be nice to open an issue in gst-ffmepg about that.

Nicolas

> 
> some issues are found
> 
> Setting pipeline to PAUSED ...
> Pipeline is PREROLLING ...
> ERROR: from element /GstPipeline:pipeline0/GstFileSrc:filesrc0: Internal data
> stream error.
> Additional debug info:
> ../subprojects/gstreamer/libs/gst/base/gstbasesrc.c(3127): gst_base_src_loop
> (): /GstPipeline:pipeline0/GstFileSrc:filesrc0:
> streaming stopped, reason error (-5)
> ERROR: pipeline doesn't want to preroll.
> Setting pipeline to NULL ...
> Freeing pipeline ...
> 
> It seems that filesrc plugin can not parse g726 raw data, do anybody give me
> some suggestion to fix the issue?
> 
> Thanks
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