[FFmpeg-devel] [PATCH v3] ffmpeg: add option -isync

Gyan Doshi ffmpeg at gyani.pro
Sat Jul 9 22:56:10 EEST 2022

On 2022-07-10 01:13 am, Paul B Mahol wrote:
> On Sat, Jul 9, 2022 at 8:28 PM Gyan Doshi <ffmpeg at gyani.pro> wrote:
>> On 2022-07-08 09:26 am, Gyan Doshi wrote:
>>> On 2022-07-07 03:11 pm, Anton Khirnov wrote:
>>>> Quoting Gyan Doshi (2022-07-04 18:29:12)
>>>>> 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 not all inputs have timestamps, the wallclock times at the time of
>>>>> reception of inputs shall be used. FFmpeg must have been compiled with
>>>>> thread support for this last case.
>>>> I'm wondering if simply using the other input's InputFile.ts_offset
>>>> wouldn't achieve the same effect with much less complexity.
>>> That's what I initially did. But since the code can also use two other
>>> sources for start times (start_time_realtime, first_pkt_wallclock),
>>> those intervals may not exactly match the difference between
>>> fmctx->start_times so I use a generic calculation.
>> Plan to push on Monday, if no further changes. 5.1 is to be cut soon.
> Why big rush, its not so critical.

Patch was first sent on 22nd June. Only one reviewer asked for changes.


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