What is the correct way to set maxrate on android ffmpeg library?

Question

I'm trying to control the max bitrate output using ffmpeg library on android.

When I use the ffmpeg command line, the output bitrate is 166.78 kbit/s

ffmpeg -y -i input.mp4 -c:v libx264 -preset medium -crf 29 -profile:v baseline -level: 3.0 -s 640x480 -strict experimental -c:a aac -ac 1 -ar 22050 -ab 48k -movflags faststart -maxrate 200k -bufsize 2000k output.mp4

But when I try using the android ffmpeg library the output bitrate is 2.12Mbit/s.

These are the options I'm passing the avcodec_open2.

av_dict_set(&opts, "preset", "medium", 0);
av_dict_set(&opts, "crf", "29", 0);
av_dict_set(&opts, "profile", "baseline", 0);
av_dict_set(&opts, "level", "30", 0);
av_dict_set(&opts, "maxrate", "200k", 0);
av_dict_set(&opts, "minrate", "0", 0);
av_dict_set(&opts, "bufsize", "2000k", 0);

/* open the codec */
ret = avcodec_open2(ctx, codec, &opts);

These are the settings in the context codec:

ctx->bit_rate = 200000;
ctx->width    = 640;
ctx->height   = 480;

Is there another setting I have to set?

I'll appreciate any help.

Thanks!

EDIT 1:

I removed the k in maxrate and bufsize but the output bitrate is still different.

For example:

ffmpeg -i input.mp4 -preset slow -c:v libx264 -maxrate 100k -bufsize 2000k -profile:v baseline -level 30 -s 480x360 -strict -2 -an output.mp4

produces an output with bitrate of 147.24 kbit/s

When running from android ffmpeg library, it produces an output with a different bitrate (99.45 kbit/s), also the video quality is reduced.

Using 200000 and 350000 as maxrate and buffsize produced a video with 157.49 kbit/s but the quality is poor compared with the command line result.

av_dict_set(&opts, "maxrate", "200000", 0);
av_dict_set(&opts, "bufsize", "350000", 0);

I did also try setting vbv-maxrate and vbv-bufsize with no luck.

What am I missing to get the same bitrate and quality when using the library?

Thanks!

Answer 1

ffmpeg lib doesn't like the "k" in numbers.

Changed values to:

av_dict_set(&opts, "maxrate", "200000", 0);
av_dict_set(&opts, "minrate", "0", 0);
av_dict_set(&opts, "bufsize", "2000000", 0);

Answer 2

crf option makes the generated file to have constant quality, this is mutually exclusive to keeping constraints on bitrate, hence remove crf option and try again.