Android MediaCodecVideoDecoder: Limit max pending frames to number of input buffers

Android MediaCodecVideoDecoder: Limit max pending frames to number of input buffers

This CL should reduce the number of timeouts for dequeueInputBuffer() which results in the log "MediaCodecVideo: dequeueInputBuffer error" followed by software fallback for VP8/VP9 and codec restart for H264.

A timeout always happen for dequeueInputBuffer() when frames_received_ > frames_decoded_ + num_input_buffers. The following code tries to drain the decoder before enqueuing more input buffers:
// Try to drain the decoder and wait until output is not too
// much behind the input.
if (frames_received_ > frames_decoded_ + max_pending_frames_) {
  ALOGV("Received: %d. Decoded: %d. Wait for output...",
      frames_received_, frames_decoded_);
  if (!DeliverPendingOutputs(jni, kMediaCodecTimeoutMs,
                             true /* dropFrames */)) {
    ALOGE << "DeliverPendingOutputs error";
    return ProcessHWErrorOnCodecThread();
  }
  if (frames_received_ > frames_decoded_ + max_pending_frames_) {
    ALOGE << "Output buffer dequeue timeout";
    return ProcessHWErrorOnCodecThread();
  }
  ...
}

However, for H264, |max_pending_frames_| can currently be larger than the number of input buffers so that the code above is never executed. This CL limits |max_pending_frames_| to the number of input buffers.

TBR=glaznev
BUG=b/24867188,b/24864151

Committed: https://crrev.com/6d387c0e92f033e31c8dd1efbf3f98bf159c6cf1
Cr-Commit-Position: refs/heads/master@{#10273}

[magjed_webrtc, 2015-10-14 09:51:44]

magjed@webrtc.org changed reviewers:
+ glaznev@webrtc.org, perkj@webrtc.org

[magjed_webrtc, 2015-10-14 09:52:18]

Please take a look.

[perkj_webrtc, 2015-10-14 10:00:05]

On 2015/10/14 09:52:18, magjed_webrtc wrote:
> Please take a look.

lgtm

[magjed_webrtc, 2015-10-14 10:04:51]

The CQ bit was checked by magjed@webrtc.org

[commit-bot: I haz the power, 2015-10-14 10:05:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1394303005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1394303005/1

[commit-bot: I haz the power, 2015-10-14 11:02:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-14 11:02:14]

Patchset 1 (id:??) landed as
https://crrev.com/6d387c0e92f033e31c8dd1efbf3f98bf159c6cf1
Cr-Commit-Position: refs/heads/master@{#10273}