Can't decode a frame when use `seek_to_frame` function

[egorsmkv]

I've wrote this code: https://github.com/egorsmkv/read-video-rs/blob/master/src/main.rs

Its goal is to read each frame per second but it seems like seek_to_frame + decode functions do not work.

Full log of a program: https://gist.github.com/egorsmkv/73f2b3d2bdd2beb63c92d3ef6018d5a4

Shortly:

Successfully sought to frame near index 0.
Frame time: 0
Successfully sought to frame near index 30.
Frame time: 8.332895221071446
Successfully sought to frame near index 60.
Frame time: 8.332895221071446
Successfully sought to frame near index 90.
Frame time: 8.332895221071446

It stuck on the second frame until the end

[gerwin3]

Can you provide some info on the input video file? Seeking only works to keyframes. In this case either the video may be short and the only keyframe is at 8.3 sec offset?

[egorsmkv]

Can you provide some info on the input video file? Seeking only works to keyframes. In this case either the video may be short and the only keyframe is at 8.3 sec offset?

wget -O "video.mp4" "https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4"

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isomavc1mp42
    creation_time   : 2010-05-17T15:28:46.000000Z
  Duration: 00:10:53.80, start: 0.000000, bitrate: 2075 kb/s
  Stream #0:0[0x1](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
      Metadata:
        creation_time   : 2010-05-17T15:28:46.000000Z
        handler_name    : (C) 2007 Google Inc. v08.13.2007.
        vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], 1947 kb/s, 24 fps, 24 tbr, 24k tbn (default)
      Metadata:
        creation_time   : 2010-05-17T15:28:46.000000Z
        handler_name    : (C) 2007 Google Inc. v08.13.2007.
        vendor_id       : [0][0][0][0]

[egorsmkv]

Also, I converted this video using a command

ffmpeg -i input.mp4 -c:v libx264 -force_key_frames "expr:gte(t,n_forced*1)" -c:a copy output.mp4

But it doesn't seem to work too

[egorsmkv]

I've managed this issue like this RustedBytes/extract-frames@b690472 for now

[gerwin3]

Thanks for the info. I will keep this open and take a look at it later. It might be that there are still some frames buffered which causes the behavior. av_seek_frame is known to be very unreliable so possibly this is an ffmpeg limitation. Anyway, I will check to confirm that later. I would suggest loading the whole video in and extracting frames that way.