RTMP playback with embedded captions causes freezing/timestamp conversion errors

[StreamMonster]

Testing RTMP streaming appliances like AJA HELO & Matrox Monarch HDX. These devices allow encoding 608 ANC/708 closed captioning data into the H.264 elementary stream. Using a dedicated Wowza Streaming Engine server on a closed network with CC enabled on these devices, picture & sometimes audio will freeze often during decode/playback. With CC turned off, the freezing stops. The Message window reports many timestamp conversion errors & discarded audio buffers, 'playback to early,' inserting zeros, etc., when CC is in the stream. This is regardless of whether or not you enable the CC track to be displayed in VLC. The CC data just needs to be present in the stream.

This doesn't occur all the time & there appears to a problem with the initial detection of the CC stream when playback is started. In the Subtitles>Subtitle Track selection, Track 1 will appear in the menu above Closed Captions 1 through "Closed Captions 4" at the start of playback sometimes & not others. When Track 1 appears is when the freezing/timestamp conversion errors appear. You can get good CC display from both the Track 1 selection as well as the Closed Captions 1 selection along with the freezes. If when you start playback & "Track 1" does NOT appear, you no longer get the freezing & errors, & you can get good captions from Closed Captions 1. Something in the initial caption detection is throwing things out of wack. All you have to do to toggle the good vs. bad state of VLC playback is stop & start stream playback several times. Track 1 will appear sometimes & not others.

Wowza support acknowledges the issue. They've tried to replicate with their internal tools as well as another 3rd party decoder & have determined it appears to be a VLC specific issue. While I've seen it on the Windows version of VLC, it appears worse on Mac. I've seen it on VLC 2.2.8 though the current 3.0.6 build.

Thanks for any insight.

[Jean-Baptiste Kempf]

Share the logs.

[StreamMonster]

Here's a sample of the log with some of the errors doing RTMP decode with CC in the elementary stream and "Track 1" showing in the Subtitles menu. Also, if you like I can send a RTMP stream to and endpoint of your choosing should you want to analyze it directly. If you need more logging, let me know where I can upload a larger attachment.

Thank you!
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main debug: VLC media player - 3.0.6 Vetinari
main debug: Copyright © 1996-2018 the VideoLAN team
main debug: revision 3.0.6-0-g5803e85f73
main debug: configured with /Users/d-fu/vlc-3.0/extras/package/macosx/../../../configure '--prefix=/Users/d-fu/vlc-3.0/build/vlc_install_dir' '--enable-macosx' '--enable-merge-ffmpeg' '--enable-osx-notifications' '--enable-faad' '--enable-flac' '--enable-theora' '--enable-shout' '--enable-ncurses' '--enable-twolame' '--enable-realrtsp' '--enable-libass' '--enable-macosx-qtkit' '--enable-macosx-avfoundation' '--disable-skins2' '--disable-xcb' '--disable-caca' '--disable-pulse' '--disable-sdl-image' '--disable-vnc' '--build=x86_64-apple-darwin17' '--host=x86_64-apple-darwin17' '--with-macosx-version-min=10.7' '--with-macosx-sdk=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk' '--with-breakpad=https://mac.crashes.videolan.org' 'build_alias=x86_64-apple-darwin17' 'host_alias=x86_64-apple-darwin17' 'CC=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang' 'CFLAGS=-g' 'LDFLAGS=' 'CXX=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++' 'CXXFLAGS=-g' 'OBJC=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang' 'OBJCFLAGS=-g'
main debug: auto hiding mouse cursor
main error: ES_OUT_SET_(GROUP_)PCR is called too late (pts_delay increased to 1000 ms)
main debug: ES_OUT_RESET_PCR called
main debug: discarded audio buffer
main debug: Buffering 0%
main debug: Received first picture
avcodec debug: available software decoder output format 0 (yuv420p)
main debug: Stream buffering done (5005 ms in 1084 ms)
main debug: Decoder wait done in 0 ms
main warning: playback way too early (-1979748): playing silence
main debug: inserting 95027 zeroes
auhal warning: underrun of 1138688 bytes
main error: ES_OUT_SET_(GROUP_)PCR is called too late (pts_delay increased to 1084 ms)
main debug: ES_OUT_RESET_PCR called
main debug: discarded audio buffer
main debug: Buffering 0%
main debug: Received first picture
avcodec debug: available software decoder output format 0 (yuv420p)
main debug: Stream buffering done (5472 ms in 255 ms)
main debug: Decoder wait done in 0 ms
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835515264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835536264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835557264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835579264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835600264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835621264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835643264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835664264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835685264 for faad
main debug: discarded audio buffer
main error: Timestamp conversion failed (delay 1084864, buffering 100000, bound 3000000)
main error: Could not convert timestamp 420835707264 for faad
main debug: discarded audio buffer

[Jean-Baptiste Kempf]

Also, if you like I can send a RTMP stream to and endpoint of your choosing should you want to analyze it directly. If you need more logging, let me know where I can upload a larger attachment.

Yes, please do.