Android视频技术探索之旅：美团外卖商家端的实践

        // VIVO Y66 模版拍摄时候，播放某些有问题的视频文件的同时去录制视频，会导致MediaServer挂掉的问题
        // 发现将1080P尺寸的配置降低到720P即可避免此问题
        // 但是720P尺寸的配置下，又存在绿边问题，因此再降到480
        if(isVIVOY66() && mMediaServerDied) {
            return getCamcorderProfile(CamcorderProfile.QUALITY_480P);
        }

        //SM-C9000,在1280 x 720 分辨率时有一条绿边。网上有种说法是GPU对数据进行了优化，使得GPU产生的图像分辨率
        //和常规分辨率存在微小差异，造成图像色彩混乱，修复后存在绿边问题。
        //测试发现，降低分辨率或者升高分辨率都可以绕开这个问题。
        if (VideoAdapt.MODEL_SM_C9000.equals(Build.MODEL)) {
            return getCamcorderProfile(CamcorderProfile.QUALITY_HIGH);
        }

        // 优先选择 1080 P的配置
        CamcorderProfile camcorderProfile = getCamcorderProfile(CamcorderProfile.QUALITY_1080P);
        if (camcorderProfile == null) {
            camcorderProfile = getCamcorderProfile(CamcorderProfile.QUALITY_720P);
        }
        // 某些机型上这个 QUALITY_HIGH 有点问题，可能通过这个参数拿到的配置是1080p，所以这里也可能拿不到
        if (camcorderProfile == null) {
            camcorderProfile = getCamcorderProfile(CamcorderProfile.QUALITY_HIGH);
        }
        // 兜底
        if (camcorderProfile == null) {
            camcorderProfile = getCamcorderProfile(CamcorderProfile.QUALITY_480P);
        }

public static double correctTimeToSyncSample(Track track, double cutHere, boolean next) {
        double[] timeOfSyncSamples = new double[track.getSyncSamples().length];
        long currentSample = 0;
        double currentTime = 0;
        for (int i = 0; i < track.getSampleDurations().length; i++) {
            long delta = track.getSampleDurations()[i];
            int index = Arrays.binarySearch(track.getSyncSamples(), currentSample + 1);
            if (index >= 0) {
                timeOfSyncSamples[index] = currentTime;
            }
            currentTime += ((double) delta / (double) track.getTrackMetaData().getTimescale());
            currentSample++;
        }
        double previous = 0;
        for (double timeOfSyncSample : timeOfSyncSamples) {
            if (timeOfSyncSample > cutHere) {
                if (next) {
                    return timeOfSyncSample;
                } else {
                    return previous;
                }
            }
            previous = timeOfSyncSample;
        }
        return timeOfSyncSamples[timeOfSyncSamples.length - 1];
}

status_t ACodec::setupVideoEncoder(const char *mime, const sp<AMessage> &msg,
       sp<AMessage> &outputFormat, sp<AMessage> &inputFormat) {
   if (!msg->findInt32("color-format", &tmp)) {
       return INVALID_OPERATION;
   }
   OMX_COLOR_FORMATTYPE colorFormat =
       static_cast<OMX_COLOR_FORMATTYPE>(tmp);
   status_t err = setVideoPortFormatType(
           kPortIndexInput, OMX_VIDEO_CodingUnused, colorFormat);
   if (err != OK) {
       ALOGE("[%s] does not support color format %d",
             mComponentName.c_str(), colorFormat);
       return err;
   }
   .......
}
status_t ACodec::setVideoPortFormatType(OMX_U32 portIndex,OMX_VIDEO_CODINGTYPE compressionFormat,
       OMX_COLOR_FORMATTYPE colorFormat,bool usingNativeBuffers) {
   ......
   for (OMX_U32 index = 0; index <= kMaxIndicesToCheck; ++index) {
       format.nIndex = index;
       status_t err = mOMX->getParameter(
               mNode, OMX_IndexParamVideoPortFormat,
               &format, sizeof(format));
       if (err != OK) {
           return err;
       }
    ......
}

status_t BufferQueueProducer::dequeueBuffer(int *outSlot,sp<android::Fence> *outFence, uint32_t width, uint32_t height,
       PixelFormat format, uint32_t usage,FrameEventHistoryDelta* outTimestamps) {
       ......
       int found = BufferItem::INVALID_BUFFER_SLOT;
       while (found == BufferItem::INVALID_BUFFER_SLOT) {
            status_t status = waitForFreeSlotThenRelock(FreeSlotCaller::Dequeue,
                      & found);
            if (status != NO_ERROR) {
                return status;
            }
        }
        ......
}
status_t BufferQueueProducer::waitForFreeSlotThenRelock(FreeSlotCaller caller,
                    int*found) const{
        ......
        while (tryAgain) {
            int dequeuedCount = 0;
            int acquiredCount = 0;
            for (int s : mCore -> mActiveBuffers) {
                if (mSlots[s].mBufferState.isDequeued()) {
                    ++dequeuedCount;
                }
                if (mSlots[s].mBufferState.isAcquired()) {
                    ++acquiredCount;
                }
            }
            // Producers are not allowed to dequeue more than
            // mMaxDequeuedBufferCount buffers.
            // This check is only done if a buffer has already been queued
            if (mCore -> mBufferHasBeenQueued &&
                    dequeuedCount >= mCore -> mMaxDequeuedBufferCount) {
                BQ_LOGE("%s: attempting to exceed the max dequeued buffer count "
                        "(%d)", callerString, mCore -> mMaxDequeuedBufferCount);
                return INVALID_OPERATION;
            }
        }
        .......
 }

status_t ACodec::configureCodec(
       const char *mime, const sp<AMessage> &msg) {
      .......
      if (encoder) {
        if (mIsVideo || mIsImage) {
          if (!findVideoBitrateControlInfo(msg, &bitrateMode, &bitrate, &quality)) {
                return INVALID_OPERATION;
            }
      } else if (strcasecmp(mime, MEDIA_MIMETYPE_AUDIO_FLAC)
           && !msg->findInt32("bitrate", &bitrate)) {
          return INVALID_OPERATION;
      }
   }
   .......
}
static bool findVideoBitrateControlInfo(const sp<AMessage> &msg,
        OMX_VIDEO_CONTROLRATETYPE *mode, int32_t *bitrate, int32_t *quality) {
    *mode = getVideoBitrateMode(msg);
    bool isCQ = (*mode == OMX_Video_ControlRateConstantQuality);
    return (!isCQ && msg->findInt32("bitrate", bitrate))
         || (isCQ && msg->findInt32("quality", quality));
}
9.0前并无对CQ码流的强校验，如果不支持该码流也会使用默认支持的码流，
static OMX_VIDEO_CONTROLRATETYPE getBitrateMode(const sp<AMessage> &msg) {
    int32_t tmp;
    if (!msg->findInt32("bitrate-mode", &tmp)) {
        return OMX_Video_ControlRateVariable;
    }
    return static_cast<OMX_VIDEO_CONTROLRATETYPE>(tmp);
}