From 2a6b0b62c396923449eeb2f06e233227dbbbdcbe Mon Sep 17 00:00:00 2001
From: Calvin Walton <calvin.walton@kepstin.ca>
Date: Wed, 17 Mar 2021 16:07:07 -0400
Subject: [PATCH] Rework the ffmpeg filter generation in the audio rendering.
This gives the following advantages over the previous code:
* The ffmpeg input filters are loaded from a filter "script" file instead
of passed on the command line. This fixes some cases of recordings
failing to process because the ffmpeg command line generated for the
audio processing exceeded the max command line length limit. (Although
that only really happens due to BBB bugs...)
* Use absolute positions when trimming audio segments for cuts.
Previously segments were trimmed to the length of the segment, and the
results were concatenated. There's some possibility of accumulated
errors in the segment lengths causing audio desync over time. The new
code incrementally concatenates the segments, and cuts each segment
end based on the absolute time since the start of the meeting, to
avoid error accumulation.
---
.../core/lib/recordandplayback/edl/audio.rb | 106 ++++++++----------
1 file changed, 46 insertions(+), 60 deletions(-)
diff --git a/record-and-playback/core/lib/recordandplayback/edl/audio.rb b/record-and-playback/core/lib/recordandplayback/edl/audio.rb
index e6c500c0d8..e5758a2815 100644
--- a/record-and-playback/core/lib/recordandplayback/edl/audio.rb
+++ b/record-and-playback/core/lib/recordandplayback/edl/audio.rb
@@ -42,7 +42,6 @@ module BigBlueButton
end
def self.render(edl, output_basename)
- sections = []
audioinfo = {}
corrupt_audios = Set.new
@@ -61,13 +60,14 @@ module BigBlueButton
audioinfo.keys.each do |audiofile|
BigBlueButton.logger.debug " #{audiofile}"
info = audio_info(audiofile)
- BigBlueButton.logger.debug " sample rate: #{info[:sample_rate]}, duration: #{info[:duration]}"
-
if !info[:audio] || !info[:duration]
BigBlueButton.logger.warn " This audio file is corrupt! It will be removed from the output."
corrupt_audios << audiofile
end
+ BigBlueButton.logger.debug " format: #{info[:format][:format_name]}, codec: #{info[:audio][:codec_name]}"
+ BigBlueButton.logger.debug " sample rate: #{info[:sample_rate]}, duration: #{info[:duration]}"
+
audioinfo[audiofile] = info
end
@@ -82,70 +82,60 @@ module BigBlueButton
dump(edl)
end
- input_index = 0
- output_index = 0
ffmpeg_inputs = []
- ffmpeg_filters = []
+ ffmpeg_filter = ''
BigBlueButton.logger.info "Generating ffmpeg command"
for i in 0...(edl.length - 1)
entry = edl[i]
audio = entry[:audio]
duration = entry[:next_timestamp] - entry[:timestamp]
- # Check for and handle audio files with mismatched lengths (generated
- # by buggy versions of freeswitch in old BigBlueButton
- if audio and entry[:original_duration] and
- (audioinfo[audio[:filename]][:duration].to_f / entry[:original_duration]) < 0.997 and
- ((entry[:original_duration] - audioinfo[audio[:filename]][:duration]).to_f /
- entry[:original_duration]).abs < 0.05
- speed = audioinfo[audio[:filename]][:duration].to_f / entry[:original_duration]
- BigBlueButton.logger.info " Using input #{audio[:filename]}"
+ ffmpeg_filter << "[a_edl#{i}_prev];\n" if i > 0
- BigBlueButton.logger.warn " Audio file length mismatch, adjusting speed to #{speed}"
-
- # Have to calculate the start point after the atempo filter in this case,
- # since it can affect the audio start time.
- # Also reset the pts to start at 0, so the duration trim works correctly.
- filter = "[#{input_index}] "
- filter << "atempo=#{speed},atrim=start=#{ms_to_s(audio[:timestamp])},"
- filter << "asetpts=PTS-STARTPTS,"
- filter << "#{FFMPEG_AFORMAT},apad,atrim=end=#{ms_to_s(duration)} [out#{output_index}]"
- ffmpeg_filters << filter
-
- ffmpeg_inputs << {
- :filename => audio[:filename],
- :seek => 0
- }
-
- input_index += 1
- output_index += 1
-
- # Normal audio input handling. Skip this input and generate silence
- # if the seekpoint is past the end of the audio, which can happen
- # if events are slightly misaligned and you get unlucky with a
- # start/stop or chapter break.
- elsif audio and audio[:timestamp] < audioinfo[audio[:filename]][:duration]
+ if audio
BigBlueButton.logger.info " Using input #{audio[:filename]}"
- filter = "[#{input_index}] "
- filter << "#{FFMPEG_AFORMAT},apad,atrim=end=#{ms_to_s(duration)} [out#{output_index}]"
- ffmpeg_filters << filter
+ speed = 1
+ seek = audio[:timestamp]
- ffmpeg_inputs << {
- :filename => audio[:filename],
- :seek => audio[:timestamp]
- }
+ # Check for and handle audio files with mismatched lengths (generated
+ # by buggy versions of freeswitch in old BigBlueButton
+ if entry[:original_duration] && (audioinfo[audio[:filename]][:duration].to_f / entry[:original_duration]) < 0.997 &&
+ ((entry[:original_duration] - audioinfo[audio[:filename]][:duration]).to_f /
+ entry[:original_duration]).abs < 0.05
+ BigBlueButton.logger.warn " Audio file length mismatch, adjusting speed to #{speed}"
+ speed = audioinfo[audio[:filename]][:duration].to_f / entry[:original_duration]
+ seek = 0
+ end
+
+ # Skip this input and generate silence if the seekpoint is past the end of the audio, which can happen
+ # if events are slightly misaligned and you get unlucky with a start/stop or chapter break.
+ if audio[:timestamp] < (audioinfo[audio[:filename]][:duration] * speed)
+ input_index = ffmpeg_inputs.length
+ ffmpeg_inputs << {
+ filename: audio[:filename],
+ seek: seek
+ }
+ ffmpeg_filter << "[#{input_index}]#{FFMPEG_AFORMAT},apad"
+ else
+ ffmpeg_filter << "#{FFMPEG_AEVALSRC},#{FFMPEG_AFORMAT}"
+ end
- input_index += 1
- output_index += 1
+ ffmpeg_filter << ",atempo=#{speed},atrim=start=#{ms_to_s(audio[:timestamp])}" if speed != 1
+ ffmpeg_filter << ",asetpts=PTS-STARTPTS"
else
BigBlueButton.logger.info " Generating silence"
- ffmpeg_filters << "#{FFMPEG_AEVALSRC},#{FFMPEG_AFORMAT},atrim=end=#{ms_to_s(duration)} [out#{output_index}]"
+ ffmpeg_filter << "#{FFMPEG_AEVALSRC},#{FFMPEG_AFORMAT}"
+ end
- output_index += 1
+ if i > 0
+ ffmpeg_filter << "[a_edl#{i}];\n"
+ ffmpeg_filter << "[a_edl#{i}_prev][a_edl#{i}]concat=n=2:a=1:v=0"
end
+
+ ffmpeg_filter << ",atrim=end=#{ms_to_s(entry[:next_timestamp])}"
end
ffmpeg_cmd = [*FFMPEG]
@@ -157,19 +147,15 @@ module BigBlueButton
end
ffmpeg_cmd += ['-i', input[:filename]]
end
- ffmpeg_filter = ffmpeg_filters.join(' ; ')
-
- if output_index > 1
- # Add the final concat filter
- ffmpeg_filter << " ; "
- (0...output_index).each { |i| ffmpeg_filter << "[out#{i}]" }
- ffmpeg_filter << " concat=n=#{output_index}:a=1:v=0"
- else
- # Only one input, no need for concat filter
- ffmpeg_filter << " ; [out0] anull"
+
+ BigBlueButton.logger.debug(' ffmpeg filter_complex_script:')
+ BigBlueButton.logger.debug(ffmpeg_filter)
+ filter_complex_script = "#{output_basename}.filter"
+ File.open(filter_complex_script, 'w') do |io|
+ io.write(ffmpeg_filter)
end
- ffmpeg_cmd += ['-filter_complex', ffmpeg_filter]
+ ffmpeg_cmd << '-filter_complex_script' << filter_complex_script
output = "#{output_basename}.#{WF_EXT}"
ffmpeg_cmd += [*FFMPEG_WF_ARGS, output]
--
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