Author Topic: oversized audio saved  (Read 834 times)

jimjulian

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oversized audio saved
« on: October 19, 2019, 01:53:30 AM »

I opened a video in Avidemux. The video is 2:33:34 (h:mm:ss) in length.
I saved the audio. The audio was 18:17:51 in length. The video has 57 chapters and is 4K.
There was an error/warning:"Referenced QT chapter track not found."
Any ideas how to determine/resolve the issue?


eumagga0x2a

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Re: oversized audio saved
« Reply #1 on: October 19, 2019, 06:22:48 AM »
Please provide textual output of MediaInfo for the video in question. If you use Windows, please provide also a compressed (zip or 7z) admlog.txt from %localappdata%\avidemux resulting from loading that video in Avidemux and saving the audio track to a file.

Avidemux doesn't support chapter marks.

jimjulian

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Re: oversized audio saved
« Reply #2 on: October 20, 2019, 07:53:37 PM »
MediaInfo:
===================== General =====================
Complete name               : D:\_4K UHD\Independence Day.4K.C24.V243-249.St.mp4
Format                      : MPEG-4
Formatprofile               : Base Media
Codec Id                    : isom (isom/iso2/avc1/mp41)
File size                   : 24.8 GB
Duration (ms)               : 2h 33mn
Overall bit rate mode       : Variable
Overall bit rate            : 23.1 Mbps
Writing application         : Lavf57.71.100

===================== Video =====================
Id                          : 1
Format                      : AVC
Format info                 : Advanced Video Codec
Formatprofile               : High@L5.1
Formatsettings, CABAC       : Yes
Formatsettings, ReFrames    : 4 frames
Codec Id                    : avc1
Codec info                  : Advanced Video Coding
Duration (ms)               : 2h 33mn
Bit rate                    : 22.9 Mbps
Width                       : 3 840 pixels
Height                      : 2 160 pixels
Display aspect ratio        : 16:9
Frame rate mode             : Constant
Frame rate                  : 24.000 fps
Color space                 : YUV
Chroma subsampling          : 4:2:0
Bit depth                   : 8 bits
Scan type                   : Progressive
Bits/(Pixel*Frame)          : 0.115
Stream size                 : 24.5 GB (99%)
Tagged date                 : UTC 2017-10-13 14:47:40
Menus                       : 0

===================== Audio =====================
Id                          : 2
Format                      : AAC
Format info                 : Advanced Audio Codec
Formatprofile               : LC
Codec Id                    : 40
Duration (ms)               : 2h 33mn
Duration_FirstFrame         : 18ms
Duration_LastFrame          : -10ms
Bit rate mode               : Variable
Bit rate                    : 243 Kbps
Maximum bit rate            : 249 Kbps
Channel(s)                  : 2 channels
Channel positions           : Front: L R
Sampling rate               : 44.1 KHz
Frame rate                  : 43.066 fps (1024 spf)
Compression mode            : Lossy
Stream size                 : 266 MB (1%)
Default                     : Yes
Alternate group             : 1
Tagged date                 : UTC 2017-10-13 14:47:40
Menus                       : 0

===================== Menu =====================

eumagga0x2a

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Re: oversized audio saved
« Reply #3 on: October 21, 2019, 11:37:07 AM »
There is nothing suspicious or irregular in the log. Also the size of saved audio track matches more or less the expected one. What gives you the duration of saved audio being over 18 hours?

The error message you cited is from libavformat's QuickTime demuxer, not from Avidemux. Was it triggered from loading the source video file or from loading Avidemux output? In which application?

Not related to the topic, but I'm curious why don't you enable DXVA2 acceleration in Avidemux, not even for display? The default "Qt" renderer means the CPU does all the scaling work instead of offloading it to the GPU which is highly optimized for this job. The integrated Intel graphics in your computer should also be able to decode H.264 and HEVC in hardware, strongly reducing energy consumption.


jimjulian

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Re: oversized audio saved
« Reply #4 on: October 21, 2019, 05:25:37 PM »
The ffprobe app and Fle Explorer yield an 18 hr reading.
The error was from ffprobe.

I played the 18 hour aac file in VLC and the 'remaining time' indicator fluctuated constantly.
The endtime in VLC was 2:44:03 even though the other indicator kept fluctuating.
The movie endtime in VLC was 2:33:34, which is correct.

Other files have simiar problems. I also have a file that came out 7hr and one at 23hr.
My concern is the occurrance of any unintended changes during edits.

jimjulian

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Re: oversized audio saved
« Reply #5 on: October 21, 2019, 05:31:02 PM »
Thanks for the DXVA2 tip.

eumagga0x2a

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Re: oversized audio saved
« Reply #6 on: October 21, 2019, 05:44:46 PM »
As ffprobe looks not very deep into the file, a stretch of highly compressible audio – like silence – can greatly skew the duration estimate for the entire stream. Don't forget that Avidemux saves audio as a raw stream, i.e. there are no structures which would allow to map a particular time to a specific offset. I assume that the issue doesn't exist as such. It is all about guessing total duration of a VBR audio stream from file size and the initial bitrate.

jimjulian

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Re: oversized audio saved
« Reply #7 on: October 21, 2019, 05:51:42 PM »
Just read your last post. My previous post verifies your findings.

This may be a good time to mention the in-app sync problems with 4K video. I replace an existing audio dub with a different one. When I first 'play' the video, everything is synchronized, but quickly loses synchronization. If I select a position later on the video, the same problem occurs. However, If I save the new video, the audio and video are synchronized.

« Last Edit: October 21, 2019, 05:54:15 PM by jimjulian »

eumagga0x2a

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Re: oversized audio saved
« Reply #8 on: October 21, 2019, 06:13:49 PM »
When I first 'play' the video, everything is synchronized, but quickly loses synchronization. If I select a position later on the video, the same problem occurs.

If audio gets ahead of video, the performance of the hardware may be insufficient for 4K in Avidemux (even with DXVA2, we still waste a lot of CPU cycles by downloading decoded vdieo data to the main memory and immediately uploading it back to the graphics card for display).