> In this case, ffplay is the wrong tool for you, ffmpeg -i input -an -f null - > may be a better idea. FFmpeg decodes a video depending on the hardware capacities, i.e., a video of 10 sec may be decoded in more than 1 mn or in only 5 sec. Therefore, FFmpeg doesn't incur miss rate (all frames are decoded and no one is dropped). To be clear, in my experiments, I want to evaluate video decoding using FFmpeg while running on multi-core. *Question:* Is there a way to decode a video using FFmpeg at a certain fps (e,g,, 25 fps) independently of the hardware capacities (*m**aybe by adding some code to FFmpeg and rebuilding it*). Of course, we will get different qualities, i.e., for example using 2 cores we will get 100 dropped frames whereas using 4 cores we will get only 5 dropped frames.
> Frames per second is > available from ffprobe, right? Yes, it gives the fps at which it is encoded. In my experiments, I need the fps while decoding the video. It is different because it depends on the hardware performance. > -f null /dev/null as I understood, this parameter allows to throw the decoded frames, i.e., the decoded frames are lost. Thank you again for all your replies. On Tue, Jun 12, 2018 at 3:27 AM Zak <ffmpeg-user-em...@m.allo.ws> wrote: > On 2018-06-11 at 5:32 PM EDT, Carl Eugen Hoyos wrote: > > 2018-06-07 23:40 GMT+02:00, mohammed bey ahmed khernache < > mohbeyi...@gmail.com>: > > > >> My purpose is to calculate some metrics such as: fps, miss rate, etc, of > >> video decoding. So I need only to decode a video without displaying it. > > > > Sorry for missing this: > > In this case, ffplay is the wrong tool for you, ffmpeg -i input -an -f > null - > > may be a better idea. > > > > Okay, I am going to ask the questions that have been on my mind for this > entire thread: > > 1. What is the goal of the original email? Frames per second is > available from ffprobe, right? Does "miss rate" refer to cache misses > while operating on the compressed video data? Won't the number of cache > misses depend on many factors, possibly including whether the computer > hardware is also busy rendering and displaying a video on the screen, > such that disabling all video display actually will change the "miss > rate"? This does not seem like a characteristic of the video file > itself, it seems like a statistic that is only available during a > specific instance of playing the video with specific software and > hardware. Or maybe I am misunderstanding. The number of cache misses may > in practice be exactly the same every time you play a given video on > certain hardware, but the original email says the test is being run > remotely on a computer that cannot display video, so any actual playback > will occur on a different computer that will have different performance, > unless I am misunderstanding. > > 2. What does ffmpeg with -f null really do, and how is it different than > ffprobe? > > Thank you, > > Zak > _______________________________________________ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".