[FFmpeg-user] CBR and bitrate

Manuel Tiglio tiglio at icloud.com
Fri Aug 11 08:50:26 EEST 2017


I have had the same problem with both CBR and constrained VBR, even with two passes, and no luck in really controlling the bitrate as specified. I posted it a couple of weeks ago but did not get anyone who could really get CBR and or 110% or 150% or any other constrained VBR or at least exactly how to reproduce any results. 


> On Aug 10, 2017, at 10:35 PM, akash kulkarni <kul.akash123 at gmail.com> wrote:
> 
> its fine @jmkhoo1 atleast you tried and its appreciated...
> input file is of constant bit rate mode after executing command i am
> getting variable bit rate...
> so question was how i get the CBR mode output
> 
> On Thu, Aug 10, 2017 at 7:59 PM, jmkhoo1 <jmkhoo1-at-yahoo.com at ffmpeg.org>
> wrote:
> 
>> Apologies. I should have tried it out first. You are correct. Even
>> specifying r:v and -b:v failed.-------- Original message --------From:
>> jmkhoo1 <jmkhoo1-at-yahoo.com at ffmpeg.org> Date: 8/10/2017  9:28 AM
>> (GMT-05:00) To: FFmpeg user questions <ffmpeg-user at ffmpeg.org> Subject:
>> Re: [FFmpeg-user] CBR and bitrate
>> If you mean a constant frame rate, use -r:v 25. If you actually mean
>> bitrate, use -b:v and -b:a. I think you might want to look at the x264
>> switches to make sure that it is encoded and a constant bit rate, though I
>> am fairly sure specifying a bit rate will do it.-------- Original message
>> --------From: akash kulkarni <kul.akash123 at gmail.com> Date: 8/10/2017
>> 7:18 AM  (GMT-05:00) To: FFmpeg user questions <ffmpeg-user at ffmpeg.org>
>> Subject: [FFmpeg-user] CBR and bitrate
>> hello everyone
>> 
>> i have file with CBR and when i am converting it to other format by using
>> following command i am getting VBR both video and audio
>> 
>> ffmpeg -i input.mp4 -y -r 25 -c:v libx264 -look_ahead 0 -preset veryfast
>> -b:v 25M -c:a aac ouput.MTS
>> 
>> so How i can get the output file in CBR mode and frame rate 25.
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