[FFmpeg-user] Audio sync issues when transcoding Hauppauge HDPVR content
Scott Naef
snaef1 at mail.brookdalecc.edu
Tue Jan 15 20:30:17 CET 2013
I am attempting to transcode recordings made with an HDPVR. I am using
Mythtv to do the capture. I originally had trouble with playback in
Myth but was able to use the environment variable
FORCE_DTS_TIMESTAMPS=1 to get proper playback in Myth. I am an
absolute newbie when it comes to the finer details of the workings of
these various media packages. I have read several places that the
HDPVR produces broken PTS timestamps. However, if there is a workable
solution to playback content in Myth, I am hoping there is a workable
solution to do transcoding with FFMPEG.
I have tried several options in FFMPEG such as -async 1 but nothing I
try seems to work. I always end up with about 1.5 second delay in
video from audio. From what I understand DTS timestamps are used to
decode content and offer a deterministic way to predict the number of
frames to decode and PTS timestamps are used to show the correct frames
in the correct order. If this is true (long shot!) then I guess I need
a way to mux the audio and video streams using DTS not PTS. Is this
way the Myth player does it?
Version:
ffmpeg version git-2013-01-05-7e5d4fa Copyright (c) 2000-2013 the FFmpeg
developers
built on Jan 5 2013 17:29:28 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
configuration: --enable-gpl --enable-libass --enable-libfaac
--enable-libfdk-aac --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-librtmp --enable-libtheora
--enable-libvorbis --enable-libvpx --enable-x11grab --enable-libx264
--enable-nonfree --enable-version3
libavutil 52. 13.100 / 52. 13.100
libavcodec 54. 85.101 / 54. 85.101
libavformat 54. 59.104 / 54. 59.104
libavdevice 54. 3.102 / 54. 3.102
libavfilter 3. 32.100 / 3. 32.100
libswscale 2. 1.103 / 2. 1.103
libswresample 0. 17.102 / 0. 17.102
libpostproc 52. 2.100 / 52. 2.100
Any help would be greatly appreciated. If needed I can grab a few
seconds of a news clip (talking heads help to see this) and offer it up
somewhere.
Thank you!
-Scott Naef
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