[FFmpeg-user] ffplay error

Carl Eugen Hoyos ceffmpeg at gmail.com
Mon Jun 18 00:17:08 EEST 2018

2018-06-17 22:40 GMT+02:00, Mohammed Bey Ahmed Khernache <mohbeyinfo at gmail.com>:
>> ffplay does not work
>> with video via ssh which I don't consider very worrying.
> This time, I am connecting the board directly to the screen
> via Micro-HDMI, and I got the same issue. That's why, I
> am sure that problem didn't come from ssh connection.

Did you try another application that uses sdl?

>>  Anything wrong with using ffmpeg
> FFmpeg works fine, without any problem. But, it can not do anything to
> reach the requested framerate (fps). For example, if a video is encoded at
> 25 fps, FFmpag can decode it at 5 fps if we use for example only one core,
> or at 60 fps if we use 8 cores. Therefore, FFmpeg decodes at the capacity
> of the hardware. I consider this as a constraint, because I can not
> calculate miss rate which is an important metric to evaluate a video
> decoder.

I may misunderstand but please believe me that ffplay is nearly
unsuitable for performance tests, many people use ffmpeg -i
input -f null - to measure libavcodec (and libavformat) performance.
You can specify what number of threads libavcodec should use for
decoding, both when using ffplay and ffmpeg.

In your example, libavcodec is not (nearly) fast enough to decode
the given video in real-time using one cpu core, from what you write
it is possible using multiple cores. While decoding (h264) often
scales badly, using more than one core is not unusual, especially
to reach a given performance.

Please remember not to top-post here, it is considered rude.

Carl Eugen

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