All Questions
13 questions
1
vote
0
answers
27
views
What ffmpeg parameters can be different between first and second pass?
I have attempted to encode a large video file with libvpx-vp9 with 2 pass encoding. The first pass took a surprisingly long time, while the second pass was unacceptably slow.
Since libvpx-vp9 can, ...
- 111
0
votes
1
answer
276
views
Creating an 8K/4K video in ffmpeg from single image frame leads to video longer than audio
I want to make a video using a cover image and an audio file with the audio file as the length. What's the most optimal modern way to do this with new codecs and high resolutions?
Reason why I want 4K/...
- 113
1
vote
1
answer
716
views
Why does setting a maximum bitrate in Constrained Quality mode sometimes increase file size?
Short version: Why did my total file size increase when I switched from constant quality to constrained quality at the same crf? Shouldn't this just set a maximum bitrate and thus only either do ...
- 11
0
votes
0
answers
594
views
Encode VP9 in mov container with pcm audio
Davinci Resolve's supported Codecs list shows it only supports decoding VP9 if placed in an mov container. Add to that the audio limitations also present on the Linux version and mov is somewhat ...
- 101
2
votes
0
answers
2k
views
ffmpeg vp9 encoding settings to produce "yuv420p(tv, progressive)"
I have a webm video that was made (from an h264) using AWS Elastic Transcoder, using the "System preset: Webm VP9 720p" preset.
For this file, ffprobe gives:
$ ffprobe converted-mp4.webm
<snip&...
- 121
1
vote
1
answer
1k
views
Encoding: Insert keyframes at certain positions
I am trying to improve the perceived quality of certain predefined frames (like the frames 45, 99, 154, ...). Reason is, that the video is interactive and pauses at these keyframes until the user ...
- 13
3
votes
0
answers
640
views
Chrome renders WebM Video "darker" than other browsers / media players
Not sure if this is the correct community, but I have a question about video encoding and decoding.
I have a video that gets served in MP4 or WebM formats, depending on browser support. I noticed ...
- 131
0
votes
2
answers
1k
views
Fast VP9 still image encoding
I use this command to create "myFile.webm", a VP9 video with one still image :
$ ffmpeg -i myOriginialPureAudioFile.opus -loop 1 -i myAudioFile_640x360.png -shortest -threads 4 -speed max -...
- 175
1
vote
1
answer
731
views
What are the WebM (VP9+opus) encoding settings compatible for YouTube import for a video with a still image?
What are the WebM (VP9+opus) encoding settings compatible for YouTube import for a video with a still image ?
I tried PAL and NTSC framerates with 48kHz stereo and and image size of 640x360 and kept ...
- 175
0
votes
2
answers
4k
views
Is it possible to use 2-pass encoding to create vp9 / webm videos from an image sequence?
I'm currently creating webm videos using ffmpeg to encode an image sequence. My command is:
ffmpeg -framerate 30 -f image2 -i frames/%04d.png -i my_audio.flac -c:v libvpx-vp9 -pix_fmt yuva420p -b:v 0 -...
- 95
5
votes
1
answer
9k
views
Is it safe to use the yuva420 pix_format option with ffmpeg to encode webm videos?
I am encoding png image sequences to both webm and mp4 formats using ffmpeg. My goal is to achieve perceptually lossless videos, with the smallest file size I can reasonably achieve.
The webm videos ...
- 95
3
votes
1
answer
4k
views
Create Alpha channel-Videos (obs stinger compatible) with ffmpeg and 2 files
I have 2 video files. One file is the main content and the other file has an alpha channel emulated with black and white (white = opacity 100 and black = opacity 0). Sometimes the emulated alpha ...
- 33
31
votes
3
answers
62k
views
Convert mp4 to webm without quality loss with ffmpeg
What is the best way to convert a mp4 file to webm without quality loss (using vp8 or vp9) with ffmpeg?
If I do ffmpeg -i in.mp4 out.webm the quality is very bad. I can specify a target bitrate via -...
- 491