layout: post title: “2024-03-19-mediaPlayer设置倍速播放.markdown” date: 2024-03-19 12:11:30 +0800

调用过程

  • App设置倍速 PlaybackParams params = uiHolder.player.getPlaybackParams(); params.setSpeed(speed); uiHolder.player.setPlaybackParams(params);
  • 进入native层 [android_media_MediaPlayer.cpp] mp->setPlaybackSettings(rate);
  • [mediaplayer.cpp] status_t err = mPlayer->setPlaybackSettings(rate);
    1. mPlayer的创建 1) getMediaPlayerService()[MediaPlayerService.cpp] 2) service->create(this, mAudioSessionId, mAttributionSource) sp c = new Client( this, verifiedAttributionSource, connId, client, audioSessionId);
  • [MediaPlayerService.cpp] 中转给player status_t MediaPlayerService::Client::setPlaybackSettings(const AudioPlaybackRate& rate) { ALOGV(“[%d] setPlaybackSettings(%f, %f, %d, %d)”, mConnId, rate.mSpeed, rate.mPitch, rate.mFallbackMode, rate.mStretchMode); sp p = getPlayer(); if (p == 0) return UNKNOWN_ERROR; return p->setPlaybackSettings(rate); }
  • [MediaPlayerService.h] sp getPlayer() const { Mutex::Autolock lock(mLock); return mPlayer; }
  • [MediaPlayerService.cpp] MediaPlayerFactory提供真正的player p = MediaPlayerFactory::createPlayer(playerType, mListener, VALUE_OR_FATAL(aidl2legacy_int32_t_pid_t(mAttributionSource.pid)));
  • [MediaPlayerFactory.cpp] factory = sFactoryMap.valueFor(playerType); CHECK(NULL != factory); p = factory->createPlayer(pid);

  • factory注册 status_t MediaPlayerFactory::registerFactory_l(IFactory* factory, player_type type) { if (NULL == factory) { ALOGE(“Failed to register MediaPlayerFactory of type %d, factory is” “ NULL.”, type); return BAD_VALUE; }

    if (sFactoryMap.indexOfKey(type) >= 0) { ALOGE(“Failed to register MediaPlayerFactory of type %d, type is” “ already registered.”, type); return ALREADY_EXISTS; }

    if (sFactoryMap.add(type, factory) < 0) { ALOGE(“Failed to register MediaPlayerFactory of type %d, failed to add” “ to map.”, type); return UNKNOWN_ERROR; }

    return OK; }

在Android系统中，MediaPlayerFactory.h中的registerFactory方法用于注册自定义的MediaPlayer工厂， 以便在需要创建MediaPlayer实例时，系统可以使用这个工厂来选择合适的MediaPlayer类型。 通常情况下，Android系统中有多种MediaPlayer实现，例如： NuPlayer：这是Android Framework层中默认的MediaPlayer实现，用于处理大多数音视频播放任务。 AwesomePlayer：这是旧版的MediaPlayer实现，用于向后兼容以及特定的音视频播放场景。 FFmpeg 或其他第三方库的播放器：Android系统允许开发者使用第三方库来扩展MediaPlayer的功能，比如使用FFmpeg库来支持更多的音视频格式。

  • [NuPlayer.cpp]
    1. setPlaybackSettings
    2. onMessageReceived case kWhatConfigPlayback:
    3. mRenderer->setPlaybackSettings(rate); new Renderer(mAudioSink, mMediaClock, notify, flags);
    4. newRate.mSpeed = mPlaybackSettings.mSpeed; mVideoDecoder->setParameters(params);