videodiff

Find time offset and scaling between two versions of the same video.

Typical usage is to sync the audio of two versions of the same video. This software compares the photage and provides an offset and scale for adjusting the target file audio so that it matches the reference file.

A image hash algorithm is used to compare frames. The image comparison is quite strict, so you cannot use it to sync different photage of the same scene from different cameras.

Requirements

ffmpeg (runtime requirement)
rust (if built from source)

Use-Case:

I built this tool to sync old TV-broadcasted dubbed anime with a bluray version to join the dubbed audio together with the improved image quality that a bluray provides.

Because of my limited use-case, I have no idea if this software works well for comparing other kinds of sources.

Build

cargo build --release

Usage

Usage: videodiff [OPTIONS] <ref_file> <target_file>

Arguments:
  <ref_file>
  <target_file>

Options:
      --skip-start <secs>  Seconds to skip at start of file
      --skip-end <secs>    Seconds to skip at end of file
  -h, --help               Print help information
  -V, --version            Print version information

An example might look like so:

videodiff ~/video_ref.mkv ~/video_target.mkv

Log:

Extracting frames from /Users/test/video_ref.mkv...
Extracting frames from /Users/test/video_target.mkv...
  - Fps: 25
Decoding frames...
  - Got 31888 images.
Computing hashes...
  - Fps: 23.976025
Decoding frames...
  - Got 30649 images.
Computing hashes...
Indexing frames...
Comparing frames... (slow)
  - Got 155 comparable frames
Optimizing offset and scale...
  - [Result] -        ss: 0.00000s, atempo: 1.00000000, error: 1000000.00
  - [Result] -        ss: 1.93146s, atempo: 1.00361616, error: 9510.17
  - [Result] - itsoffset: 6.48952s, atempo: 1.00187226, error: 6831.05
  - [Result] -        ss: 3.07356s, atempo: 0.99189467, error: 4045.38
  - [Result] - itsoffset: 5.11055s, atempo: 1.00167032, error: 3877.90
  - [Result] - itsoffset: 4.51322s, atempo: 1.00166945, error: 2812.60
  - [Result] - itsoffset: 3.91662s, atempo: 1.00166944, error: 1950.80
  - [Result] - itsoffset: 3.32061s, atempo: 1.00166944, error: 1292.43
  - [Result] - itsoffset: 2.72520s, atempo: 1.00166944, error: 842.11
  - [Result] - itsoffset: 2.13039s, atempo: 1.00166944, error: 620.97
  - [Result] - itsoffset: 1.53617s, atempo: 1.00166944, error: 620.45
  - [Result] -        ss: 0.77154s, atempo: 0.99892964, error: 365.63
  - [Result] -        ss: 0.18084s, atempo: 0.99892991, error: 68.28
  - [Result] - itsoffset: 0.20129s, atempo: 0.99892991, error: 31.95
  - [Result] - itsoffset: 0.04572s, atempo: 0.99892991, error: 26.72
  - [Result] - itsoffset: 0.15528s, atempo: 0.99901764, error: 24.67

This can be used with ffmpeg to sync like so:

ffmpeg -i ~/video_ref.mkv -itsoffset 0.15528 -i ~/video_target.mkv -filter:a:1 "atempo=0.99901764" -map 0 -map 1:a -c:v copy -c:a:0 copy -c:a:1 libopus -b:a:1 96k ~/out.mkv

I still don't understand

Look at the discussions here and see if it helps.

Notes

More options should probably be tunable via cli.

This is very much untested software, use at own risk.

Gronis / videodiff

readme