Hey guys,
this is going to be nerdy and crazy technical, but I am a nerd and I like getting to the bottom of something as far as I can.
I have sync issues when importing video in REAPER.
I am working on a movie which was encoded with the Avid DNxHD Codec.
Code:
General
Complete name : D:\SomeVideo.mov
Format : MPEG-4
Commercial name : DNxHD 36
Format profile : QuickTime
Codec ID : qt 2005.03 (qt )
File size : 2.93 GiB
Duration : 11 min 29 s
Overall bit rate : 36.5 Mb/s
Encoded date : UTC 2017-04-06 17:21:08
Tagged date : UTC 2017-04-06 17:39:30
Writing library : Apple QuickTime
Video
ID : 2
Format : VC-3
Commercial name : DNxHD 36
Format version : Version 1
Format profile : HD@LB
Codec ID : AVdn
Codec ID/Info : Avid DNxHD
Duration : 11 min 29 s
Bit rate mode : Constant
Bit rate : 36.2 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 24.000 FPS
Color space : YUV
Chroma subsampling : 4:2:2
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.727
Stream size : 2.90 GiB (99%)
Title : Apple Video Mediensteuerung / Apple Alias-Datensteuerung
Language : English
Encoded date : UTC 2017-04-06 17:21:09
Tagged date : UTC 2017-04-06 17:39:30
Audio
ID : 1
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 11 min 29 s
Source duration : 11 min 29 s
Bit rate mode : Constant
Bit rate : 320 kb/s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 spf)
Compression mode : Lossy
Stream size : 26.5 MiB (1%)
Source stream size : 26.5 MiB (1%)
Title : Apple Ton Mediensteuerung / Apple Alias-Datensteuerung
Language : English
Encoded date : UTC 2017-04-06 17:21:09
Tagged date : UTC 2017-04-06 17:39:29
Other
ID : 3
Type : Time code
Format : QuickTime TC
Duration : 11 min 29 s
Time code of first frame : 09:59:50:00
Time code, striped : Yes
Title : Apple Zeitmarken-Mediensteuerung / Apple Alias-Datensteuerung
Language : English
Encoded date : UTC 2017-04-06 17:39:29
Tagged date : UTC 2017-04-06 17:39:29
The video has audio embedded in it for syncing, it also came with an AAF for post production and when I import the video into ProTools, it syncs up nicely.
https://i.imgur.com/6b54ZXg.png
I exported the audio stems from PT, imported them into REAPER and then imported the video. It does not sync up. I played with REAPER's video decoder settings and when I use QT for decoding, there is a two sample difference between video-embedded audio and the audio stem.
https://i.imgur.com/zRwigpO.png
When I use my favorite decoder, vlc (it just works), there is a huge delay in the video's audio:
https://i.imgur.com/DiMf58i.png
Over 2000 samples!
So what's going on here and how can I fix it?
Interesting note - only the video's audio is affected. The test tone in the exported audio stem from PT starts exactly where the "test tone frame" starts in the video, no matter what decoder I use. The issue is with the audio here.
I appreciate any help and maybe this thread will help others too, once we found a solution.