Latency and misc fixes

[j0sh]

• Reduce segmenter ffmpeg's analyzeduration to 2s. This avoids waiting for audio during RTMP pull at the risk of missing late tracks, especially video with a long GOP.

• Send current segment immediately when the publisher is ready to receive data, rather than waiting for the next segment. This reduces time-to-first-frame at the risk of higher perceived latency if playback happens to start at the current segment (which we are effectively buffering, instead of staying on the leading edge by waiting for the next segment)

• Rearrange retry sleeps in the segmenter: if ffmpeg needs to retry, it will immediately check for stream existence and exit if necessary. If the stream still exists, only then will it sleep for 5 seconds. This avoids a 5 second delay in signaling EOF.

• Add some comments around how retries are still kinda broken anyway

• Fix a couple of missing body closes in mediamtx HTTP request handling

• Log ffmpeg output on rtmp pull errors

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 19 lines in your changes missing coverage. Please review.

Project coverage is 32.13857%. Comparing base (0f9be6a) to head (3687f1f).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
media/rtmp2segment.go	0.00000%	8 Missing ⚠️
media/segment_reader.go	0.00000%	8 Missing ⚠️
media/mediamtx.go	0.00000%	2 Missing ⚠️
server/ai_live_video.go	0.00000%	1 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3401         +/-   ##
===================================================
- Coverage   32.15038%   32.13857%   -0.01181%     
===================================================
  Files            147         147                 
  Lines          40830       40845         +15     
===================================================
  Hits           13127       13127                 
- Misses         26928       26943         +15     
  Partials         775         775                 

Files with missing lines	Coverage Δ
server/ai_live_video.go	0.00000% <0.00000%> (ø)
media/mediamtx.go	0.00000% <0.00000%> (ø)
media/rtmp2segment.go	3.38983% <0.00000%> (-0.08843%)	⬇️
media/segment_reader.go	0.00000% <0.00000%> (ø)

... and 2 files with indirect coverage changes

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Files with missing lines	Coverage Δ
server/ai_live_video.go	0.00000% <0.00000%> (ø)
media/mediamtx.go	0.00000% <0.00000%> (ø)
media/rtmp2segment.go	3.38983% <0.00000%> (-0.08843%)	⬇️
media/segment_reader.go	0.00000% <0.00000%> (ø)

... and 2 files with indirect coverage changes

[leszko]

Looks good from my end. Thanks for the fixes Josh!

[j0sh]

Also added a 2.5s analyzeduration to the output side of ffmpeg. That should trim a couple seconds off the output delay - it's not much but something for now.