[FFmpeg-user] Generating bloated videos

Cecil Westerhof Cecil at decebal.nl
Sat Jun 3 14:59:18 EEST 2023

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

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