Body: <p>Several files generated in XAVC have 2 B-frames before the I-frame and I've been trying to transcode those files using <code>ffmpeg</code> to match the structure at a lower resolution/bitrate, but I've been unable to do so. I was hoping that <code>-force_key_frames source</code> would do that, but it always makes the first frame a key frame, so is there a way to match the <code>pict_type</code> and have 2 B-frames before the I-frame while transcoding with <code>ffmpeg</code>?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-09-21T04:22:30.727Z
Comments.Text: How are you determining the order of the frames in the source?
Comments.UserDisplayName: Gyan
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-09-24T18:10:00.750Z
Comments.Text: This command outputs the frames and then also stepping through the `ffmpeg` code with a debugger:
  `ffprobe -show_entries frame=pts,pkt_pos,pict_type -of csv=p=0 -I test.mp4`
Comments.UserDisplayName: Dave Johansen
Tags: <ffmpeg><transcoding><keyframes>
Title: Generating B-frames before I-frame with ffmpeg (like XAVC)
UserDisplayName: Dave Johansen
ThreadText: # Generating B-frames before I-frame with ffmpeg (like XAVC)
  
  (Asked by: username_0 on 2024-09-21)
  
  Several files generated in XAVC have 2 B-frames before the I-frame and I've been trying to transcode those files using `ffmpeg` to match the structure at a lower resolution/bitrate, but I've been unable to do so. I was hoping that `-force_key_frames source` would do that, but it always makes the first frame a key frame, so is there a way to match the `pict_type` and have 2 B-frames before the I-frame while transcoding with `ffmpeg`?
  
  **Tags:** ffmpeg, transcoding, keyframes
  
  > **Comments:**
  > **username_1**: How are you determining the order of the frames in the source?  
  > **username_0**: This command outputs the frames and then also stepping through the `ffmpeg` code with a debugger: `ffprobe -show_entries frame=pts,pkt_pos,pict_type -of csv=p=0 -I test.mp4`  
  
  ---
  
  ## 0 answers
  
  