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H264: Thread-safe InitializeFFmpeg. Flag to control if InitializeFFmpeg should be called.

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New flag: rtc_initialize_ffmpeg, default value = !build_with_chromium.

In WebRTC standalone we initialize FFmpeg by default, in Chromium we don't by default.
Chromium is an external project that also use FFmpeg. If both projects do FFmpeg initialization code things will break. The flag makes it possible for other external projects than chromium to decide whether or not WebRTC should initialize FFmpeg.

BUG=chromium:500605, chromium:468365, webrtc:5427

Review URL: https://codereview.webrtc.org/1639273002

Cr-Commit-Position: refs/heads/master@{#11456}
This commit is contained in:
hbos
2016-02-02 02:26:05 -08:00
committed by Commit bot
parent 799379e8c2
commit c5a39c2591
5 changed files with 43 additions and 12 deletions
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3
webrtc/modules/video_coding/BUILD.gn
View File

@ -140,6 +140,9 @@ source_set("webrtc_h264") {
if (rtc_use_h264) {
defines += [ "WEBRTC_THIRD_PARTY_H264" ]
if (rtc_initialize_ffmpeg) {
defines += [ "WEBRTC_INITIALIZE_FFMPEG" ]
}
sources += [
"codecs/h264/h264_decoder_impl.cc",
"codecs/h264/h264_decoder_impl.h",

7
webrtc/modules/video_coding/codecs/h264/h264.gypi
View File

@ -27,6 +27,13 @@
'defines': [
'WEBRTC_THIRD_PARTY_H264',
],
'conditions': [
['rtc_initialize_ffmpeg==1', {
'defines': [
'WEBRTC_INITIALIZE_FFMPEG',
],
}],
],
'dependencies': [
'<(DEPTH)/third_party/ffmpeg/ffmpeg.gyp:ffmpeg',
'<(DEPTH)/third_party/openh264/openh264.gyp:openh264_encoder',

25
webrtc/modules/video_coding/codecs/h264/h264_decoder_impl.cc
View File

@ -34,8 +34,9 @@ const size_t kYPlaneIndex = 0;
const size_t kUPlaneIndex = 1;
const size_t kVPlaneIndex = 2;
#if !defined(WEBRTC_CHROMIUM_BUILD)
#if defined(WEBRTC_INITIALIZE_FFMPEG)
rtc::CriticalSection ffmpeg_init_lock;
bool ffmpeg_initialized = false;
// Called by FFmpeg to do mutex operations if initialized using
@ -61,10 +62,8 @@ int LockManagerOperation(void** lock, AVLockOp op)
return -1;
}
// TODO(hbos): Assumed to be called on a single thread. Should DCHECK that
// InitializeFFmpeg is only called on one thread or make it thread safe.
// See https://bugs.chromium.org/p/webrtc/issues/detail?id=5427.
void InitializeFFmpeg() {
rtc::CritScope cs(&ffmpeg_init_lock);
if (!ffmpeg_initialized) {
if (av_lockmgr_register(LockManagerOperation) < 0) {
RTC_NOTREACHED() << "av_lockmgr_register failed.";
@ -75,7 +74,7 @@ void InitializeFFmpeg() {
}
}
#endif // !defined(WEBRTC_CHROMIUM_BUILD)
#endif // defined(WEBRTC_INITIALIZE_FFMPEG)
// Called by FFmpeg when it is done with a frame buffer, see AVGetBuffer2.
void AVFreeBuffer2(void* opaque, uint8_t* data) {
@ -179,13 +178,15 @@ int32_t H264DecoderImpl::InitDecode(const VideoCodec* codec_settings,
return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
}
// In Chromium FFmpeg will be initialized outside of WebRTC and we should not
// attempt to do so ourselves or it will be initialized twice.
// TODO(hbos): Put behind a different flag in case non-chromium project wants
// to initialize externally.
// See https://bugs.chromium.org/p/webrtc/issues/detail?id=5427.
#if !defined(WEBRTC_CHROMIUM_BUILD)
// Make sure FFmpeg has been initialized.
// FFmpeg must have been initialized (with |av_lockmgr_register| and
// |av_register_all|) before we proceed. |InitializeFFmpeg| does this, which
// makes sense for WebRTC standalone. In other cases, such as Chromium, FFmpeg
// is initialized externally and calling |InitializeFFmpeg| would be
// thread-unsafe and result in FFmpeg being initialized twice, which could
// break other FFmpeg usage. See the |rtc_initialize_ffmpeg| flag.
#if defined(WEBRTC_INITIALIZE_FFMPEG)
// Make sure FFmpeg has been initialized. Subsequent |InitializeFFmpeg| calls
// do nothing.
InitializeFFmpeg();
#endif