Fix AVC encoder selection on some MTK devices: try non-secure encoders before *.secure

[anilateapp]

Describe the bug
On some MediaTek/Transsion devices, H.264 encoder selection may pick a secure encoder first
(for example c2.mtk.avc.encoder.secure).

That encoder appears to be intended for DRM / protected-content pipelines. With a normal
camera + Surface/GL streaming path, it may configure successfully but produce no usable
video output.

In practice, RTMP sends audio only:

• audio packets are written
• no SPS/PPS callback for video
• no encoded video output
• no video packets written

After moving secure video encoders to the end of the candidate list, the device selects
a normal AVC encoder and streaming works correctly.

To Reproduce

1. Run streaming on an affected MediaTek/Transsion device
2. Start an RTMP stream using H.264 video
3. Let the library select the default video encoder
4. Observe that c2.mtk.avc.encoder.secure is selected
5. Observe that audio is sent but video is not

Expected behavior
A normal non-secure AVC encoder should be selected first when available, so camera streaming
produces normal H.264 video output and RTMP sends both audio and video.

Screenshots
N/A

Smartphone (please complete the following information):

• Library version: 2.7.1
• Device: [your Transsion device model here]
• OS: [your Android version here]
• Media server: [your RTMP server here]
• Class used: GenericStream

Additional context
I verified this against a working Qualcomm device, where a normal non-secure AVC encoder is selected
and both audio/video are sent correctly.

On the affected MTK device, selecting a non-secure encoder fixes the issue.

Local fix:

• move secure video encoders after normal candidates in VideoEncoder
• deprioritize secure video encoders in CodecUtil

[pedroSG94]

Hello,

Thank you for the report. Fixed here:
cdafdd5

[anilateapp]

I still need this additional safeguard in VideoEncoder.chooseEncoder().

The CodecUtil change alone was not enough on my affected MTK/Transsion device.
Without this, a .secure AVC encoder could still be selected in the final encoder
selection path, and I still got audio-only RTMP output.

@Override
protected MediaCodecInfo chooseEncoder(String mime) {
  List<MediaCodecInfo> mediaCodecInfoList;
  if (codecType == CodecUtil.CodecType.HARDWARE) {
    mediaCodecInfoList = CodecUtil.getAllHardwareEncoders(mime, true);
  } else if (codecType == CodecUtil.CodecType.SOFTWARE) {
    mediaCodecInfoList = CodecUtil.getAllSoftwareEncoders(mime, true);
  } else if (codecType == CodecUtil.CodecType.CBR_PRIORITY) {
    mediaCodecInfoList = CodecUtil.getAllEncodersCbrPriority(mime);
  } else {
    mediaCodecInfoList = CodecUtil.getAllEncoders(mime, true, true);
  }

  mediaCodecInfoList = moveSecureVideoEncodersLast(mediaCodecInfoList);

  Log.i(TAG, mediaCodecInfoList.size() + " encoders found");
  for (MediaCodecInfo mci : mediaCodecInfoList) {
    ...
  }
}

  /**
   * Secure encoders are for protected content; for camera streaming they are often listed as the
   * only HW AVC encoder but do not produce output without crypto.
   */
  private static List<MediaCodecInfo> moveSecureVideoEncodersLast(List<MediaCodecInfo> encoders) {
    List<MediaCodecInfo> preferred = new ArrayList<>();
    List<MediaCodecInfo> secure = new ArrayList<>();
    for (MediaCodecInfo info : encoders) {
      if (isSecureVideoEncoderName(info.getName())) {
        secure.add(info);
      } else {
        preferred.add(info);
      }
    }
    preferred.addAll(secure);
    return preferred;
  }

  private static boolean isSecureVideoEncoderName(String name) {
    if (name == null) {
      return false;
    }
    String lower = name.toLowerCase(Locale.US);
    return lower.contains(".secure") && lower.contains("encoder") && !lower.contains("aac");
  }

[pedroSG94]

Hello,

I was looking more info about secure codecs and it is used only for DRM/secure content so it is not usable for this library. For that reason I decided totally discard that codecs here:
d1612a5

Please, test with the library app example and confirm that all is working as expected.

[anilateapp]

@pedroSG94 I made changes() to 2.7.2 and the stream started working

[pedroSG94]

Ok,
This will be available in the next release