Hi,
I mean I'm encoding with the MPEG4 codec. Initialized as:
AVCodec * codec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
I have little experience with the ffmpeg application. I mostly use libav
API. There is an example though here :
https://trac.ffmpeg.org/wiki/Encode/MPEG-4
That shows how to encode with the mpeg4 codec at a constant 555k bitrate:
ffmpeg -y -i input.avi -c:v mpeg4 -vtag xvid -b:v 555k -pass 1 -an -f
avi /dev/null
I don't know how to achieve that using the libav api. Here is a copy of
my previous mail in case formatting was off:
--------------
I have an application that encodes mpeg4 video. The encoder was an
adaptation of the decoding_encoding_8c-example
(https://www.ffmpeg.org/doxygen/2.4/decoding_encoding_8c-example.html).
It works well, but bitrate fluctuates without much control. Currently,
these are my AVCodecContext settings:
c->bit_rate = 5000000;
c->width = this->m_width;
c->height = this->m_height;
c->time_base.den = 25;
c->time_base.num = 1;
c->gop_size = 0;
c->max_b_frames=0;
c->pix_fmt = AV_PIX_FMT_YUV420P;
av_opt_set(c->priv_data, "preset", "ultrafast", 0);
av_opt_set(c->priv_data, "tune", "zerolatency", 0);
And I get up to 70Mbps depending on the image being encoded. I have also
tried to set these parameters:
c->bit_rate = 12e06;
c->rc_min_rate = c->bit_rate;
c->rc_max_rate = c->bit_rate;
c->rc_buffer_size = c->bit_rate * 30;
And it does limit bandwidth, but after a couple minutes of encoding I
get the error:
[error] ffmpeg error evaluating rc_eq (null)
My guess is that I'm missing some parameters. I don't quite understand
what the rc_buffer_size value should be either.
---------------------
El 16-Oct-14 a las #4, Carl Eugen Hoyos escribió:
Sergio Basurco <sergio.b@...> writes:
av_opt_set(c->priv_data, "preset", "ultrafast", 0);
av_opt_set(c->priv_data, "tune", "zerolatency", 0);
I don't know what you mean with "mpeg4 video" but
I believe these are not supported for "mpeg4"
encoding.
Did you test with ffmpeg (the application)? It
should tell you if it is possible at all to
reach the desired bitrate for your input file
and your options.
(If possible, please set your mailer to "text-only",
your mails are hard to read here.)
Carl Eugen
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--
Sergio Basurco,
Coherent Synchro
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