Thanks for the reply! I tested it against a ffmpeg command doing approximately the same (except manipulating the individual frames, slightly different duration):
ffmpeg -ss 00:06:48.27 -i IN.mp4 -c:v mpeg4 -c:a copy -t 00:01:11.89
-b:v 7257k OUT.mp4
This outputs
Stream #0:0(eng): Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 1920x1080
[SAR 1:1 DAR 16:9], q=2-31, 7257 kb/s, 12800 tbn, 25 tbc (default)
and generates a file of size 67.1 MB (roughly matches the expected size - 7722
kb/s).
> At least constant quantizer vs. bitrate can (and must) be set.
bitrate is clear, constant quantizer matches which field and should be set to
which value?
Greetings Harald
-
Harald Schlangmann
Antwerpener Str. 52, 50672 Köln, Germany
+49 151 2265 4439
[email protected]
www.gps-laptimer.de
On 20.04.2014, at 17:25, Carl Eugen Hoyos <[email protected]> wrote:
> Harald Schlangmann <harry@...> writes:
>
>> Looks I’m doing something fundamentally wrong here.
>
> Did you test with ffmpeg (the application)?
> I am not convinced that single pass encoding can
> generally guarantee a target bitrate.
>
>> Any hint on how to influence result file size for mpeg4?
>
>> The only other fields I initialize for AVCodecContext
>> are width, height, time_base, pix_fmt,
>
> At least constant quantiser vs. bitrate can (and must)
> be set.
>
> Carl Eugen
>
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