How force a constant bit rate for audio created with ffmpeg?

Starduster · 12th October 2020, 02:25

I'm putting title pages between video clips and concatenating them together so I need all the clips to be the same. I am creating the title slides with:

Code:

fa=Tone(length=3.0, type="Silence", samplerate=22050, channels=2)
v=BlankClip(90, 960, 540, pixel_type="RGB24", fps=29.97).ConvertToYV12(matrix="rec709").AddAlphaPlane()
AudioDub(v, fa).Subtitle("This is a test", align=5, size=24)

I'm creating the .mp4 clip using ffmpeg with:

Code:

ffmpeg -i gsn_10.avs -b:a 128 gsn_10.mp4

if I use -b:a 128k or don't use that parameter at all, it becomes variable rate and I need constant rate. Using the -b:a 128 makes it constant, but the bit rate doesn't change.

MediaInfo gives: "Bit rate: 1 084 b/s" and all other clips have "Bit rate: 128 kb/s"

The bit rate is the only difference in the clips. When I concat them with:

Code:

ffmpeg -f concat -safe 0 -i render.txt -c copy highlight.mp4

I get a ton of "Non-monotonous DTS in output stream" errors.

The resulting .mp4 is 19+ hours long when I should be about 6 minutes.

So, is there a way to force a constant bit rate of 128kb in AviSynth or do I need to find another way to do that in ffmpeg.

12th October 2020, 02:25	#1 \| Link
Starduster Registered User Join Date: Jun 2007 Location: Ann Arbor, MI Posts: 124	How force a constant bit rate for audio created with ffmpeg? I'm putting title pages between video clips and concatenating them together so I need all the clips to be the same. I am creating the title slides with: Code: fa=Tone(length=3.0, type="Silence", samplerate=22050, channels=2) v=BlankClip(90, 960, 540, pixel_type="RGB24", fps=29.97).ConvertToYV12(matrix="rec709").AddAlphaPlane() AudioDub(v, fa).Subtitle("This is a test", align=5, size=24) I'm creating the .mp4 clip using ffmpeg with: Code: ffmpeg -i gsn_10.avs -b:a 128 gsn_10.mp4 if I use -b:a 128k or don't use that parameter at all, it becomes variable rate and I need constant rate. Using the -b:a 128 makes it constant, but the bit rate doesn't change. MediaInfo gives: "Bit rate: 1 084 b/s" and all other clips have "Bit rate: 128 kb/s" The bit rate is the only difference in the clips. When I concat them with: Code: ffmpeg -f concat -safe 0 -i render.txt -c copy highlight.mp4 I get a ton of "Non-monotonous DTS in output stream" errors. The resulting .mp4 is 19+ hours long when I should be about 6 minutes. So, is there a way to force a constant bit rate of 128kb in AviSynth or do I need to find another way to do that in ffmpeg. __________________ Life is more interesting viewed upside down