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Integrate Constant Rate Factor (CRF) for FFmpegWriter (#186)

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* First implementation of CRF (Constant Rate Factor)

* Include AV1 in the codecs that can use crf

* First version that uses SetOption to set crf quality

* Clarify comments

* Delete setting the bitrate for crf in SetVideoOption because it
is not needed, it is set later with SetOptions.
This commit is contained in:
Jonathan Thomas
2019-01-25 00:15:07 -06:00
committed by GitHub
parent c4321f3f8e
commit 0587ada6dc
1 changed files with 39 additions and 3 deletions
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42
src/FFmpegWriter.cpp
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@@ -146,7 +146,7 @@ void FFmpegWriter::SetVideoOptions(bool has_video, string codec, Fraction fps, i
info.pixel_ratio.num = pixel_ratio.num;
info.pixel_ratio.den = pixel_ratio.den;
}
if (bit_rate >= 1000)
if (bit_rate >= 1000) // bit_rate is the bitrate in b/s
info.video_bit_rate = bit_rate;
info.interlaced_frame = interlaced;
@@ -237,7 +237,8 @@ void FFmpegWriter::SetOption(StreamType stream, string name, string value)
// Was option found?
if (option || (name == "g" || name == "qmin" || name == "qmax" || name == "max_b_frames" || name == "mb_decision" ||
name == "level" || name == "profile" || name == "slices" || name == "rc_min_rate" || name == "rc_max_rate"))
name == "level" || name == "profile" || name == "slices" || name == "rc_min_rate" || name == "rc_max_rate" ||
name == "crf"))
{
// Check for specific named options
if (name == "g")
@@ -284,6 +285,39 @@ void FFmpegWriter::SetOption(StreamType stream, string name, string value)
// Buffer size
convert >> c->rc_buffer_size;
else if (name == "crf") {
// encode quality and special settings like lossless
// This might be better in an extra methods as more options
// and way to set quality are possible
#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(55, 39, 101)
switch (c->codec_id) {
case AV_CODEC_ID_VP8 :
av_opt_set_int(c->priv_data, "crf", min(stoi(value),63), 0);
break;
case AV_CODEC_ID_VP9 :
av_opt_set_int(c->priv_data, "crf", min(stoi(value),63), 0);
if (stoi(value) == 0) {
av_opt_set_int(c->priv_data, "lossless", 1, 0);
}
break;
case AV_CODEC_ID_H264 :
av_opt_set_int(c->priv_data, "crf", min(stoi(value),51), 0);
break;
case AV_CODEC_ID_H265 :
av_opt_set_int(c->priv_data, "crf", min(stoi(value),51), 0);
if (stoi(value) == 0) {
av_opt_set_int(c->priv_data, "lossless", 1, 0);
}
break;
#ifdef AV_CODEC_ID_AV1
case AV_CODEC_ID_AV1 :
av_opt_set_int(c->priv_data, "crf", min(stoi(value),63), 0);
break;
#endif
}
#endif
}
else
// Set AVOption
AV_OPTION_SET(st, c->priv_data, name.c_str(), value.c_str(), c);
@@ -934,7 +968,9 @@ AVStream* FFmpegWriter::add_video_stream()
#endif
/* Init video encoder options */
c->bit_rate = info.video_bit_rate;
if (info.video_bit_rate > 1000) {
c->bit_rate = info.video_bit_rate;
}
//TODO: Implement variable bitrate feature (which actually works). This implementation throws
//invalid bitrate errors and rc buffer underflow errors, etc...