Convertion of Png image into yuv420p format codec mpeg2video.

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Convertion of Png image into yuv420p format codec mpeg2video.

shivkumar munugala
Hi ,

I am using below command to convert png into yuv420p
Command :
ffmpeg -async 1 -i *boot_up_1.png* -vcodec mpeg2video -r 25 -pix_fmt
yuv420p -minrate 50000k -maxrate 50000k -b 50000k -intra  -ps 1000M -qmin 1
-qmax 3 -top 1 -bufsize 2000000 -an output_iframetest_7_test.m2v

input file:
* boot_up_1.png*
output file:

*output_iframetest_7_test.m2v*
Problem:
Lower file size image less than 10Kb, when converted using above command
it's giving higher file size than input.
Higher file size image more than 414kb, when converted, output file size in
less.

Question:
Why this behaviour? . Either it should increase the output file size or
reduce, why both behaviour?


Warm regards,
Shivkumar Munugala
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Re: Convertion of Png image into yuv420p format codec mpeg2video.

Moritz Barsnick
On Thu, Oct 18, 2018 at 18:49:48 +0530, shivkumar munugala wrote:
> I am using below command to convert png into yuv420p
> Command :
> ffmpeg -async 1 -i *boot_up_1.png* -vcodec mpeg2video -r 25 -pix_fmt
> yuv420p -minrate 50000k -maxrate 50000k -b 50000k -intra  -ps 1000M -qmin 1
> -qmax 3 -top 1 -bufsize 2000000 -an output_iframetest_7_test.m2v
[...]
> Lower file size image less than 10Kb, when converted using above command
> it's giving higher file size than input.
> Higher file size image more than 414kb, when converted, output file size in
> less.
>
> Question:
> Why this behaviour? . Either it should increase the output file size or
> reduce, why both behaviour?

You misunderstand. All your output options, such as "-minrate 50000k -maxrate 50000k -b
50000k" tell ffmpeg exactly how large the output shall be, *regardless*
of the input. ffmpeg is doing its best to achieve that.

And even in any other case: How large the output gets, depends on a lot
of encoder details, but also on the (uncompressed) image content of the
input. You can have small but complex (hard to compress) inputs, and
also large simple (easy to compress) inputs.

In the future, please also show us the complete, uncut console output
from your ffmpeg command. There is a lot of valuable information in
there which helps finding and pointing out issues.

Moritz
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