audiotestsrc vs. multifilesrc

[Paul Harbison]

I had similar problems when using live sources and adding in wav files 
at any time. I solved it by using multisrc (not a filesrc) and applying 
a time offset to the mixer sinkpad;

See: 
https://stackoverflow.com/questions/69624156/adding-10-second-wav-file-to-gstreamer-pipeline-that-is-already-playing/69717638#69717638



On 14/01/2022 12:17 am, Marianna Smidth Buschle via gstreamer-devel wrote:
>
> Hello,
>
> I strongly believe I have experienced similar issues, but related to 
> images/video instead of audio.
>
> Your basic problem is that 'multifilesrc' is not a live source, while 
> you use the 'audiotestsrc' as live.
>
> That basically means that while a live source will produce buffers 
> based on the configured timing (from CAPS), the non-live source will 
> produce buffers as fast as possible (or as fast as the downstream 
> elements tell it to).
>
> You can try checking the difference by doing:
>
> audiotestsrc is-live=true wave=ticks ! audio/x-raw,format=S16LE,rate=48000,channels=1 ! autoaudiosink sync=true
>
> And
>
> audiotestsrc is-live=true wave=ticks ! audio/x-raw,format=S16LE,rate=48000,channels=1 ! autoaudiosink sync=false
>
> For the live source you shouldn't see any difference.
> But I expect that you will see for the non-live, depending on using 
> 'autoaudiosink sync=true' or 'autoaudiosink sync=false'
>
> multifilesrc do-timestamp=true loop=true location=count.wav ! wavparse ignore-length=1 ! audio/x-raw,format=S16LE,rate=48000,channels=1 ! autoaudiosink sync=false
>
>
> Now, the way I managed to have file sources working as "live sources" 
> for me was by adding either a 'identity sync=true' or 'clocksync' to 
> the pipeline.
> Something like:
>
> multifilesrc do-timestamp=true loop=true location=count.wav ! wavparse ignore-length=1 ! audio/x-raw,format=S16LE,rate=48000,channels=1 ! clocksync ! autoaudiosink sync=false
>
>
> Now, I do remember some issues with 'multifilesrc', so I would 
> recommend trying also with 'filesrc' instead.
>
>
> And I was using H264 streams packed to MPEG-TS, in this case it would 
> only work after the demuxer:
>
> gst-launch-1.0 filesrc location=/tmp/test1.ts ! tsdemux name=demux :
> queue ! identity sync=true ! h264parse ! avdec_h264 qos=false ! 
> videoconvert ! ximagesink
> demux. : queue ! identity sync=true ! decodebin : audioconvert ! 
> autoaudiosink
>
>
> Note that I haven't tested any of the pipelines besides this last one, 
> which comes from my own project...
>
>
> Best Regards
>
> Marianna S. Buschle
>
>
> On 13.01.2022 13.00, gstreamer-devel-request at lists.freedesktop.org wrote:
>> Hello everyone,
>>
>> I'm having an issue here that's probably very simple, but I can't see what's wrong.
>>
>> I've been using the following audio source for testing in my larger WebRTC pipeline:
>>
>> audiotestsrc is-live=true wave=ticks !
>> audio/x-raw,format=S16LE,rate=48000,channels=1 ! tee allow-not-linked=true
>> name=audiotestsrc
>>
>> Now I've tried to replace it with an audiofile of a voice counting (to estimate
>> delay etc.):
>>
>> multifilesrc do-timestamp=true loop=true location=count.wav ! wavparse
>> ignore-length=1 ! audio/x-raw,format=S16LE,rate=48000,channels=1 ! tee
>> allow-not-linked=true name=audiotestsrc
>>
>> The audiofile does have S16LE/48kHz/mono, so there shouldn't be any format
>> issues. Both variants work when I run them in gst-launch-1.0 and append an
>> autoaudiosink at the end; I can even replicate the encoder pipeline by appending
>> "... ! queue ! opusenc ! rtpopuspay ! queue max-size-time=100000000 !
>> rtpopusdepay ! opusdec ! autoaudiosink" and it still works for both of them.
>>
>> However, when I connect the encoder output to webrtcbin within my larger
>> pipeline, then the multifilesrc seems to never start streaming. Caps negotiation
>> and WebRTC SDP negotiation both complete and seem to be fine, but I'm never
>> actually getting an audiostream unless I keep using audiotestsrc (or e.g.
>> alsasrc/pulsesrc, those work as well).
>>
>> For the curious, audiofile in question is here:
>> https://floe.butterbrot.org/external/count.wav
>>
>> Any suggestions?
>>
>> Thanks and best regards, Florian
> -- 
> Best regards / Med venlig hilsen
> “Marianna Smidth Buschle”

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