Blank frames between requests in CUE playlist

[vitoyucepi]

Describe the bug
If playlist uses a CUE file, it will produce blank frames when switching between requests.

To Reproduce

1. ffmpeg -f lavfi -i "sine=frequency=100:duration=2" -c:a libmp3lame -b:a 16k -y 1.mp3
2. 1.cue

   FILE "/tmp/test/1.mp3" WAVE
     TRACK 01 AUDIO
       INDEX 01 00:00:00
     TRACK 02 AUDIO
       INDEX 01 00:01:00

3. main.liq

   s = playlist("1.cue", loop=false, mode="normal")
   
   s = clock(sync="none", s)
   # clock.assign_new(sync="none", [s])
   
   enc = %ffmpeg(format="mp3", %audio(codec="libmp3lame", b="128k"))
   output.file(enc, "out.mp3", s, fallible=true)
   

Expected behavior
No blank frames between requests, because they produce an audible click.

Version details

• OS: debian in docker
• Version: 2.2.5, c46726b

Install method
savonet/liquidsoap:v2.2.5

Common issues
#3937

[toots]

Thanks for reporting. I am not sure if this is really a bug. The gap is caused by the new request taking too much time to be prepared I think. If I use prefetch=2, I get a constant sine (with a pop due to the expected discontinuity between the tracks):

[vitoyucepi]

If I use prefetch=2

This is weird. There are only two tracks in the playlist and I still see the gap even with prefetch=2.

[toots]

What decoder are you using?

[vitoyucepi]

I found this issue a good opportunity to test github actions, and I didn't enjoy the process.
https://github.com/vitoyucepi/liquidsoap-issue-3971
https://github.com/vitoyucepi/liquidsoap-issue-3971/blob/52ecedb16e84924d5340611b1fe7ebd4c5775fdd/.github/workflows/github-actions-demo.yml
https://github.com/vitoyucepi/liquidsoap-issue-3971/actions/runs/9602151400/job/26482345377

What decoder are you using?

ffmpeg