[FFmpeg-user] Generating bloated videos

[Cecil Westerhof]

Bouke / edit 'B <bouke at editb.nl> writes:

>> On 3 Jun 2023, at 12:37, Cecil Westerhof via ffmpeg-user <ffmpeg-user at ffmpeg.org> wrote:
>> 
>> I am not knowledgeable in the fine points of video processing, so it
>> is possible that I ask for something that is not realistic.
>> 
>> Sometimes the output stream becomes bigger as the input stream and I
>> find this strange.
>> In the past I used:
>>    -vcodec libx264 -crf 26
>
> 26 is bad quality, 23 is default, stick to that. (Good quality /
> small size)

As I said: I did not see any difference when using 26 with the
original. A long time ago I did a lot of experimenting and this what I
(then) saw as most optimal regarding time and size.

But I forgot an important point I come back on later in this email.


>> and this gave videos that I saw no difference in and where often
>> 1/14th of the original size.
>> 
>> But sometimes they become bigger.
>> 
>> For example I have an input file of 117.5 MB.
>> If I use:
>>    ffmpeg -i ${inputfile}           \
>>           -vcodec libx264           \
>>           -crf 28                   \
>>           -af "volume=${volumeCmd}" \
>>           -y ${outputfile}
>
> Perhaps input file has compressed audio and output file uncompressed?
>
>
>> the output file becomes 129.4 MB.
>> 
>> Well that could be because of the audio filter.
>> But when I do:
>>    ffmpeg -i ${inputfile}           \
>>           -vcodec copy              \
>>           -af "volume=${volumeCmd}" \
>>           -y ${outputfile}
>> 
>> the output file becomes 110.7 MB. Almost 2/13 smaller.
>> 
>> This seems strange to me, or am I missing something?
>
> The size also has to do with the encoding speed
> You can gain some bits if you give FFmpeg more time.
> Try ‘-preset slower’ in your line.

The funny thing was in the past I had speed and smaller size with:
    -preset veryfast

I try the different options again and come back.

Stupid that I forgot the -preset. :'-(

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof