[FFmpeg-devel] [PATCH v2] avcodec: add realtime bitstream filter

[Gyan]

On 02-05-2019 04:12 PM, Moritz Barsnick wrote:
> On Wed, May 01, 2019 at 12:03:41 -0300, James Almer wrote:
>>> +    if (pkt->pts != AV_NOPTS_VALUE) {
>>> +        int64_t pts = av_rescale_q(pkt->pts, bsf->time_base_in, AV_TIME_BASE_Q) / ctx->speed;
>>> +        int64_t now = av_gettime_relative();
>>> +        int64_t sleep = pts - now + ctx->delta;
>>> +        if (!ctx->inited) {
>>> +            ctx->inited = 1;
>>> +            sleep = 0;
>>> +            ctx->delta = now - pts;
>> If this is meant to be used for input, where seeking can take place,
>> wouldn't a flush() callback to set ctx->inited and ctx->delta back to 0
>> be needed?
> Interesting point. I suppose you mean backward seeking. Is that a valid
> use case for a bitstream filter? Would it also apply to the standard
> filter, where I took this code from?
>
> I don't know, but I can try to add that, if required. Can you tell me
> how to emulate or test seeking from the command line? Would I create a
> file with backward jumps in PTS (and how)?

Also, you may want to add support for -copyts which -re lacks as well. 
Another complication is timestamp rollover, independent of copyts.

How does the filter behave with non-monotonic timestamps?

Gyan

P.S. you can craft files to test all of this by generating individual TS 
files with custom timestamps and then 'cat'ting them together, whether 
via the concat protocol or shell utility.