[FFmpeg-user] why in the world does WMV ignore the bitrate

Reindl Harald h.reindl at thelounge.net
Tue Oct 29 16:16:47 CET 2013


Am 29.10.2013 16:08, schrieb James Darnley:
> On 2013-10-29 14:29, Reindl Harald wrote:
>> 4,2M 2013-10-29 14:21 output.wmv
>> 71M 2013-10-29 10:19 input.mp4
>>
>> ffmpeg -i output.wmv:
>> Input #0, asf, from 'output.wmv':
>>   Metadata:
>>     major_brand     : mp42
>>     minor_version   : 0
>>     compatible_brands: mp42mp41
>>     creation_time   : 2013-10-29T14:21:35
>>     encoder         : Lavf55.19.104
>>   Duration: 00:00:20.13, start: 0.000000, bitrate: 1715 kb/s
>>     Stream #0:0: Video: wmv2 (WMV2 / 0x32564D57), yuv420p, 1080x1920, 25 tbr, 1k tbn, 1k tbc
>>     Stream #0:1: Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, stereo, fltp, 128 kb/s
> 
> Dare I say but this reported bitrate is correct for the video's stats.
> 4.2MiB / 20s = 1750 kbps
> 
>> frame=   49 fps=0.0 q=24.8 size=     745kB time=00:00:01.96 bitrate=3112.3kbits/s dup=1 drop=0
>> frame=   99 fps= 99 q=31.0 size=    1160kB time=00:00:03.96 bitrate=2400.2kbits/s dup=1 drop=0
>> frame=  152 fps=100 q=31.0 size=    1535kB time=00:00:06.08 bitrate=2068.6kbits/s dup=1 drop=0
>> frame=  202 fps=100 q=31.0 size=    1923kB time=00:00:08.21 bitrate=1916.4kbits/s dup=1 drop=0
>> frame=  252 fps=100 q=31.0 size=    2276kB time=00:00:10.08 bitrate=1849.6kbits/s dup=1 drop=0
>> frame=  302 fps= 99 q=31.0 size=    2645kB time=00:00:12.08 bitrate=1793.5kbits/s dup=1 drop=0
>> frame=  352 fps= 99 q=31.0 size=    3023kB time=00:00:14.08 bitrate=1758.7kbits/s dup=1 drop=0
>> frame=  407 fps=100 q=31.0 size=    3479kB time=00:00:16.34 bitrate=1743.6kbits/s dup=1 drop=0
>> frame=  457 fps=100 q=24.8 size=    3898kB time=00:00:18.34 bitrate=1740.7kbits/s dup=1 drop=0
>> frame=  501 fps=100 q=31.0 Lsize=    4217kB time=00:00:20.04 bitrate=1723.7kbits/s dup=2 drop=0
>> video:3808kB audio:313kB subtitle:0 global headers:0kB muxing overhead 2.320599%
> 
> It appears that the encoder cannot compress the video any smaller with
> your current settings. It is too large and/or too complex

size does not matter, the problem is the unacceptable quality until i raise up to Mbit's
ffmpeg -i 'input.mp4' -y -vb '20480k' -an -vcodec 'wmv2' -acodec 'wmav2' 'output.wmv'

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