Question / Help Extract audio from corrupt MP4

[ggguy]

So I recorded about 2 hours of footage yesterday only to have it cut off by the 15 second warning prompt (very counterproductive). As a result, the video is unwatchable. Now, I was able to "repair" a part of it with a third party tool, however it only ends up being about a fourth of the original length with half of this version being "watchable," as it's also highly artifacted and sped up.

Now I know at this is because of the missing moov atom file, which I have yet to find any fix for (I'm pretty certain it's gone). However, given that this was a screen recording of a Skype call, I was wondering if it is still possible to extract and recover the audio stream as that is the only thing I really need. Is the audio affected in the same way as the video or can it actually be saved?

Here is what I believe is the log file given the length of it:

Spoiler

22:27:11: CLR host plugin strings not found, dynamically loading 4 strings
22:27:11: CLRHost::Initialize() attempting to load and start the .NET runtime (null)
22:27:11: CLRHost::Initialize() Found version v2.0.50727 .NET runtime
22:27:11: CLRHost::Initialize() Found version v4.0.30319 .NET runtime
22:27:11: CLRHost::Initialize() attempting to use v4.0.30319 .NET runtime
22:27:11: CLRHost::LoadInteropLibrary() load the assembly plugins\CLRHostPlugin\CLRHost.Interop.dll
22:27:12: CLRHost::LoadPlugins() attempting to load the plugin assembly CLRBrowserSourcePlugin
22:27:12: CLRHost:: Could not find/load browser settings at location C:\Users\gibba_000\AppData\Roaming\OBS\pluginData\browser.json
22:27:12: CLRHost:: Exception: System.IO.FileNotFoundException: Could not find file 'C:\Users\gibba_000\AppData\Roaming\OBS\pluginData\browser.json'.
22:27:12: File name: 'C:\Users\gibba_000\AppData\Roaming\OBS\pluginData\browser.json'
22:27:12: at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
22:27:12: at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
22:27:12: at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
22:27:12: at CLRBrowserSourcePlugin.Shared.BrowserSettings.Reload()
22:27:12: CLRHost::LoadPlugins() successfully added CLR plugin [Type: CLRBrowserSourcePlugin.CLRBrowserSourcePlugin, Name: CLR Browser Source Plugin]
22:27:14: Open Broadcaster Software v0.658b - 64bit (　^ω^)
22:27:14: -------------------------------
22:27:14: CPU Name: Intel(R) Core(TM) i7-4700HQ CPU @ 2.40GHz
22:27:14: CPU Speed: 2394MHz
22:27:14: Physical Memory: 12170MB Total, 8195MB Free
22:27:14: stepping id: 3, model 60, family 6, type 0, extmodel 1, extfamily 0, HTT 1, logical cores 8, total cores 4
22:27:14: monitor 1: pos={0, 0}, size={1920, 1080}
22:27:14: monitor 2: pos={1906, 1080}, size={1920, 1080}
22:27:14: Windows Version: 10.0 Build 14393 (revision 0)
22:27:14: Aero is Enabled
22:27:14: -------------------------------
22:27:14: OBS Modules:
22:27:14: Base Address Module
22:27:14: 0000000093460000 OBS.exe
22:27:14: 0000000088CD0000 OBSApi.dll
22:27:14: 000000009E540000 CLRHostPlugin.dll
22:27:14: 000000009DC50000 DShowPlugin.dll
22:27:14: 0000000097230000 GraphicsCapture.dll
22:27:14: 000000009E2F0000 NoiseGate.dll
22:27:14: 000000009DEB0000 PSVPlugin.dll
22:27:14: 000000009AA50000 scenesw.dll
22:27:14: ------------------------------------------
22:27:14: Adapter 1
22:27:14: Video Adapter: Intel(R) HD Graphics 4600
22:27:14: Video Adapter Dedicated Video Memory: 117964800
22:27:14: Video Adapter Shared System Memory: 2147483648
22:27:14: Video Adapter Output 1: pos={0, 0}, size={1920, 1080}, attached=true
22:27:14: Video Adapter Output 2: pos={1906, 1080}, size={1920, 1080}, attached=true
22:27:14: ------------------------------------------
22:27:14: Adapter 2
22:27:14: Video Adapter: NVIDIA GeForce GTX 860M
22:27:14: Video Adapter Dedicated Video Memory: 2116943872
22:27:14: Video Adapter Shared System Memory: 2086119424
22:27:14: =====Stream Start: 2016-08-23, 22:27:14===============================================
22:27:14: Multithreaded optimizations: On
22:27:14: Base resolution: 1280x720
22:27:14: Output resolution: 1280x720
22:27:14: ------------------------------------------
22:27:14: Loading up D3D10 on Intel(R) HD Graphics 4600 (Adapter 1)...
22:27:14: ------------------------------------------
22:27:14: Audio Format: 48000 Hz
22:27:14: ------------------------------------------
22:27:14: Audio Channels: 2 Ch
22:27:14: Playback device Default
22:27:14: ------------------------------------------
22:27:14: Using desktop audio input: Speakers (Realtek High Definition Audio)
22:27:14: Global Audio time adjust: 0
22:27:14: ------------------------------------------
22:27:14: Using auxilary audio input: Microphone (Yeti Stereo Microphone)
22:27:14: Mic time offset: 0
22:27:14: ------------------------------------------
22:27:14: Audio Encoding: AAC
22:27:14: bitrate: 128
22:27:14: Using Monitor Capture
22:27:14: Scene buffering time set to 700
22:27:14: ------------------------------------------
22:27:14: Video Encoding: x264
22:27:14: fps: 60
22:27:14: width: 1280, height: 720
22:27:14: preset: veryfast
22:27:14: profile: high
22:27:14: keyint: 250
22:27:14: CBR: yes
22:27:14: CFR: yes
22:27:14: max bitrate: 5000
22:27:14: buffer size: 5000
22:27:14: ------------------------------------------
22:27:30: FlushBufferedVideo: Flushing 21 packets over 334 ms
22:27:30: Total frames encoded: 924, total frames duplicated: 0 (0.00%)
22:27:30: Total frames rendered: 953, number of late frames: 0 (0.00%) (it's okay for some frames to be late)
22:27:30:
22:27:30: Profiler time results:
22:27:30:
22:27:30: ==============================================================
22:27:30: video thread frame - [100%] [avg time: 0.723 ms] [children: 29.5%] [unaccounted: 70.5%]
22:27:30: | scene->Preprocess - [16.5%] [avg time: 0.119 ms]
22:27:30: | GPU download and conversion - [13%] [avg time: 0.094 ms] [children: 10.1%] [unaccounted: 2.9%]
22:27:30: | | flush - [5.53%] [avg time: 0.04 ms]
22:27:30: | | CopyResource - [3.73%] [avg time: 0.027 ms]
22:27:30: | | conversion to 4:2:0 - [0.83%] [avg time: 0.006 ms]
22:27:30: Convert444Threads - [100%] [avg time: 2.204 ms] [children: 99.7%] [unaccounted: 0.318%]
22:27:30: | Convert444toNV12 - [99.7%] [avg time: 2.197 ms]
22:27:30: encoder thread frame - [100%] [avg time: 0.847 ms] [children: 8.5%] [unaccounted: 91.5%]
22:27:30: | sending stuff out - [8.5%] [avg time: 0.072 ms]
22:27:30: ==============================================================
22:27:30:
22:27:30:
22:27:30: Profiler CPU results:
22:27:30:
22:27:30: ==============================================================
22:27:30: video thread frame - [cpu time: avg 0.672 ms, total 640.625 ms] [avg calls per frame: 1]
22:27:30: | scene->Preprocess - [cpu time: avg 0 ms, total 0 ms] [avg calls per frame: 1]
22:27:30: | GPU download and conversion - [cpu time: avg 0.016 ms, total 15.625 ms] [avg calls per frame: 1]
22:27:30: | | flush - [cpu time: avg 0.016 ms, total 15.625 ms] [avg calls per frame: 1]
22:27:30: | | CopyResource - [cpu time: avg 0 ms, total 0 ms] [avg calls per frame: 1]
22:27:30: | | conversion to 4:2:0 - [cpu time: avg 0 ms, total 0 ms] [avg calls per frame: 1]
22:27:30: Convert444Threads - [cpu time: avg 1.927 ms, total 3484.38 ms] [avg calls per frame: 2]
22:27:30: | Convert444toNV12 - [cpu time: avg 1.927 ms, total 3484.38 ms] [avg calls per frame: 2]
22:27:30: encoder thread frame - [cpu time: avg 0.553 ms, total 500 ms] [avg calls per frame: 1]
22:27:30: | sending stuff out - [cpu time: avg 0 ms, total 0 ms] [avg calls per frame: 1]
22:27:30: ==============================================================
22:27:30:
22:27:30: =====Stream End: 2016-08-23, 22:27:30=================================================
22:27:32: CLR host plugin instance deleted; removing dynamically loaded localization strings
22:27:32: Terminating 0x21c4

 

[Banyarola]

I don't know if this will help but when I want to pull just the audio from an MP4 file I use Format Factory, which is free, and then save the MP4 as an MP3 and it saves just the audio.

 

[Fenrir]

You'd need to do some major manual hex editing of the file to properly recover it.

This is why you don't record to .mp4 directly. Record to .flv or .mkv and remux after if you have to.

 

[ggguy]

You'd need to do some major manual hex editing of the file to properly recover it.

This is why you don't record to .mp4 directly. Record to .flv or .mkv and remux after if you have to.

For the audio alone, is that actually possible?

 

[ggguy]

Well, I have no idea how, but a friend of mine from across the pond actually managed to repair the video in its entirety. Must be some of that European magic. God bless him.