WEBRTC 支持H264编解码-蒲公英云

WEBRTC 支持H264编解码

WEBRTC视频编解码支持H264 VP8 VP9 但是默认是VP8 ，根据SDP描述协商

WEBRTC H264编码采用OPENH264 解码采用FFMPEG

一让WEBRTC支持H264编码

修改配置支持H264编码

webrtc/build/common.gypi rtc_use_h264=1(只要有都设为1)，这样OPENH264就会生成

然后需要重新编译 Python webrtc/build/gyp_webrtc ninja -C out/Debug

2 修改SDP生成次序

webrtcvideoengine2.cc DefaultVideoCodecList 可以修改SDP中视频编码的次序把

放在最前面，让SDP支持H264

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if (CodecIsInternallySupported(kH264CodecName)) {
VideoCodec codec = MakeVideoCodecWithDefaultFeedbackParams(
kDefaultH264PlType, kH264CodecName);
// TODO(hta): Move all parameter generation for SDP into the codec
// implementation, for all codecs and parameters.
// TODO(hta): Move selection of profile-level-id to H.264 codec
// implementation.
// TODO(hta): Set FMTP parameters for all codecs of type H264.
codec.SetParam(kH264FmtpProfileLevelId,
kH264ProfileLevelConstrainedBaseline);
codec.SetParam(kH264FmtpLevelAsymmetryAllowed, “1”);
codec.SetParam(kH264FmtpPacketizationMode, “1”);
codecs.push_back(codec);
codecs.push_back(
VideoCodec::CreateRtxCodec(kDefaultRtxH264PlType, kDefaultH264PlType));
}

二让WEBRTC支持H264解码
thirdpart 下有ffmpeg源码，不用下载ffmpeg编译
1.修改gyp配置支持ffmpeg编译<webrtc/build/common.gypi rtc_initialize_ffmpeg=1
2.默认ffmpeg 不会把h264.c等文件编译进ffmpeg 就会导致 H264DecoderImpl::InitDecode 调用 avcodec_find_decoder 失败，
找不到解码器需要修改 ffmpeg_generated.gypi 默认只支持chrome chromeOS中编译H264，找到h264.c
然后在Linux X64 中去掉chrome

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[‘(OS == “linux” and target_arch == “arm” and arm_neon == 1 and ffmpeg_branding == “Chrome”) or (OS == “linux” and target_arch == “arm” and arm_neon == 1 and ffmpeg_branding == “ChromeOS”) or (OS == “linux” and target_arch == “arm” and ffmpeg_branding == “Chrome”) or (OS == “linux” and target_arch == “arm” and ffmpeg_branding == “ChromeOS”) or (OS == “linux” and target_arch == “arm64” and ffmpeg_branding == “Chrome”) or (OS == “linux” and target_arch == “arm64” and ffmpeg_branding == “ChromeOS”) or (OS == “linux” and target_arch == “ia32” and ffmpeg_branding == “Chrome”) or (OS == “linux” and target_arch == “ia32” and ffmpeg_branding == “ChromeOS”) or (OS == “linux” and target_arch == “mipsel” and ffmpeg_branding == “Chrome”) or (OS == “linux” and target_arch == “mipsel” and ffmpeg_branding == “ChromeOS”) or (OS == “linux” and target_arch == “x64” and ffmpeg_branding == “Chrome”) or(OS == “linux” and target_arch == “x64”)or (OS == “mac” and target_arch == “x64” and ffmpeg_branding == “Chrome”) or (OS == “win” and target_arch == “ia32” and ffmpeg_branding == “Chrome”) or (OS == “win” and target_arch == “x64” and ffmpeg_branding == “Chrome”)’, {

再找到

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‘libavcodec/x86/h264_qpel.c’,
‘libavcodec/x86/h264chroma_init.c’,
‘libavcodec/x86/h264dsp_init.c’,

对应得

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[‘(OS == “linux” and target_arch == “ia32” and ffmpeg_branding == “Chrome”) or (OS == “linux” and target_arch == “ia32” and ffmpeg_branding == “ChromeOS”) or (OS == “linux” and target_arch == “x64” and ffmpeg_branding == “Chrome”) or (OS == “linux” and target_arch == “x64”) or (OS == “mac” and target_arch == “x64” and ffmpeg_branding == “Chrome”) or (OS == “win” and target_arch == “ia32” and ffmpeg_branding == “Chrome”) or (OS == “win” and target_arch == “x64” and ffmpeg_branding == “Chrome”)’, {

在LINUX X64 中去掉chrome

3.重新生成ninja python webrtc/build/gyp_webrtc ninja -C out/Debug

可在video_send_stream.cc 函数，中调试 encoded_image._buffer 看码流或写入文件

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