[FFmpeg-devel] ffplay buffer

[Dan Gordon]

I’m working on a frame accurate stream switch. My current iteration is using vapoursynth to serve frames to ffplay. I have the vapoursynth script set up to take a keyboard input and then change to stream without skipping forward to the next iframe. There is a 500 ms delay between the keyboard action and the video switching. The good news is that it is frame accurate, the bad news is that 500 ms is a LONG delay. My initial assumption was that ffplay had a buffer in place but I dropped the MIN_FRAMES to 5 from 25 and the delay is still present (and still at ~500 ms).

I know this isn’t a vapoursynth forum but I’m trying to eliminate ffplay as the source of the delay. When ffplay is receiving data from a yuv4mpegpipe with MIN_FRAMES set to 5, how much of a delay is there between receiving the frames and displaying them? What are the EXTERNAL_CLOCK_MIN_FRAMES AND EXTERNAL_CLOCK_MAX_FRAMES for?

here’s my command

vspipe  -y4m script.vpy - | ffplay pipe: -sync video

Thanks


> On Aug 28, 2015, at 9:25 AM, Marton Balint <cus at passwd.hu> wrote:
> 
> On Thu, 27 Aug 2015, Dan Gordon wrote:
> 
>> I am trying to reduce the size of the buffer for ffplay, it looks like the default is around 500 ms. I have been looking through the code but unfortunately, I’m struggling with understanding it as I’m not too familiar with c yet. Can somebody point me in the right direction on how to reduce this default value?
>> 
> 
> The packet buffer size is controlled by MIN_FRAMES.
> 
> Regards,
> Marton
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