[FFmpeg-devel] [PATCH v2 2/2] ffmpeg: add option -isync

[Anton Khirnov]

Quoting Gyan Doshi (2022-07-01 13:03:04)
> 
> 
> On 2022-07-01 03:33 pm, Anton Khirnov wrote:
> > Quoting Gyan Doshi (2022-06-25 10:29:51)
> >> This is a per-file input option that adjusts an input's timestamps
> >> with reference to another input, so that emitted packet timestamps
> >> account for the difference between the start times of the two inputs.
> >>
> >> Typical use case is to sync two or more live inputs such as from capture
> >> devices. Both the target and reference input source timestamps should be
> >> based on the same clock source.
> > If both streams are using the same clock, then why is any extra
> > synchronization needed?
> 
> Because ffmpeg.c normalizes timestamps by default. We can keep 
> timestamps using -copyts, but these inputs are usually preprocessed 
> using single-input filters which won't have access to the reference 
> inputs,

No idea what you mean by "reference inputs" here.

> or the merge filters like e.g. amix don't sync by timestamp.

amix does seem to look at timestamps.

-- 
Anton Khirnov