mp4 files size problem

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mp4 files size problem

Daniel
Hello Everyone,

I have tried to convert some videos to mp4 format what has surprised me
was the size of the videos, After the conversion some videos were 2,3,4
times bigger then the original wmv files. Here is the command i used to
convert :  /usr/local/bin/ffmpeg -i video500.wmv -c:a libfdk_aac -c:v
nvenc_h264  video500.mp4 ; After this command the mp4 file is 630MB  and
the wmv file is 150MB (you can find attached the ffprobe to bothe
files). If you can suggest any way on how to keep the quality and make
the mp4 files smaller please let me know .


ps: On some mp4 videos the bitrate has doubled have no idea why ?


BR


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Re: mp4 files size problem

Cley Faye
2017-09-07 15:57 GMT+02:00 Daniel <[hidden email]>:

> Hello Everyone,
>
> I have tried to convert some videos to mp4 format what has surprised me
> was the size of the videos, After the conversion some videos were 2,3,4
> times bigger then the original wmv files. Here is the command i used to
> convert :  /usr/local/bin/ffmpeg -i video500.wmv -c:a libfdk_aac -c:v
> nvenc_h264  video500.mp4 ; After this command the mp4 file is 630MB  and
> the wmv file is 150MB (you can find attached the ffprobe to bothe files).
> If you can suggest any way on how to keep the quality and make the mp4
> files smaller please let me know .
>
>
> ps: On some mp4 videos the bitrate has doubled have no idea why ?
>

​If you don't supply your own settings, ffmpeg (and/or the underlying
codec) will assume some default values, not necessarily in compliance with
the input. In your case, you probably want (at least) to set the bitrate.
Also, I think that hardware encoder tend to produce bigger file for same
quality (and worse quality for same size), but this might not be accurate
anymore.​
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Re: mp4 files size problem

Carl Eugen Hoyos-2
In reply to this post by Daniel
2017-09-07 15:57 GMT+02:00 Daniel <[hidden email]>:

> I have tried to convert some videos to mp4 format what has surprised me was
> the size of the videos, After the conversion some videos were 2,3,4 times
> bigger then the original wmv files. Here is the command i used to convert :
> /usr/local/bin/ffmpeg -i video500.wmv -c:a libfdk_aac -c:v nvenc_h264
> video500.mp4

Complete, uncut console output missing.

You did not specify a bitrate, so I assume you did not care about the
size of the output file, is that wrong?

What is the resulting file size if you encode with libx264?

Carl Eugen
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Re: mp4 files size problem

Daniel
In reply to this post by Cley Faye
Thank you for the reply . I think you are right about the hardware
encoder . I have encoded the video with libx264 and the output file was
189MB. Do you know what is the difference between nvenc_h264 and
h264_nvenc  encoders ?


On 7.09.2017 17:09, Cley Faye wrote:

> 2017-09-07 15:57 GMT+02:00 Daniel <[hidden email]>:
>
>> Hello Everyone,
>>
>> I have tried to convert some videos to mp4 format what has surprised me
>> was the size of the videos, After the conversion some videos were 2,3,4
>> times bigger then the original wmv files. Here is the command i used to
>> convert :  /usr/local/bin/ffmpeg -i video500.wmv -c:a libfdk_aac -c:v
>> nvenc_h264  video500.mp4 ; After this command the mp4 file is 630MB  and
>> the wmv file is 150MB (you can find attached the ffprobe to bothe files).
>> If you can suggest any way on how to keep the quality and make the mp4
>> files smaller please let me know .
>>
>>
>> ps: On some mp4 videos the bitrate has doubled have no idea why ?
>>
> ​If you don't supply your own settings, ffmpeg (and/or the underlying
> codec) will assume some default values, not necessarily in compliance with
> the input. In your case, you probably want (at least) to set the bitrate.
> Also, I think that hardware encoder tend to produce bigger file for same
> quality (and worse quality for same size), but this might not be accurate
> anymore.​
> _______________________________________________
> ffmpeg-user mailing list
> [hidden email]
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email
> [hidden email] with subject "unsubscribe".

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Re: mp4 files size problem

James Girotti
On Thu, Sep 7, 2017 at 9:52 AM, Daniel <[hidden email]> wrote:

> Thank you for the reply . I think you are right about the hardware encoder
> . I have encoded the video with libx264 and the output file was 189MB. Do
> you know what is the difference between nvenc_h264 and h264_nvenc  encoders
> ?


From what I can tell from the source code "nvenc_h264" is an alias for
"h264_nvenc", but "nvenc_h264" is the old deprecated name. So you if you're
writing any scripts/programs you should use "h264_nvenc"
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