mixStreams function

Future<List<Stream>> mixStreams({ required MixStreamsOptions options, })

Mixes video and audio streams and participants based on specified parameters.

Combines alVideoStreams, nonAlVideoStreams, and refParticipants by interleaving muted and unmuted streams, while ensuring prioritized positioning for streams with specific identifiers.

• options (MixStreamsOptions): The options for mixing streams.
  • alVideoStreams (List<Stream>): List of "al" category video and audio streams to mix.
  • nonAlVideoStreams (List<Stream>): List of non-"al" category streams to mix.
  • refParticipants (List<Stream>): List of reference participants.

Returns: A Future<List<Stream>> that completes with the mixed streams list.

Example:

final mixedStreams = await mixStreams(
  options: MixStreamsOptions(
    alVideoStreams: [stream1, stream2],
    nonAlVideoStreams: [participant1, participant2],
    refParticipants: [participant1, participant2],
  ),
);
print('Mixed streams: $mixedStreams');

Throws: If an error occurs during the process of mixing streams, it logs the error in debug mode and rethrows it.

Implementation

Future<List<Stream>> mixStreams({
  required MixStreamsOptions options,
}) async {
  try {
    List<Stream> alVideoStreams = List.from(options.alVideoStreams);
    List<Stream> nonAlVideoStreams = List.from(options.nonAlVideoStreams);
    var refParticipants = options.refParticipants;

    var mixedStreams = <Stream>[];

    // Identify "youyou" or "youyouyou" stream
    var youyouStream = alVideoStreams.firstWhere(
      (obj) => obj.producerId == 'youyou' || obj.producerId == 'youyouyou',
      orElse: () => Stream(
        producerId: '',
        name: '',
        muted: false,
      ),
    );

    alVideoStreams = alVideoStreams
        .where((obj) =>
            obj.producerId != 'youyou' && obj.producerId != 'youyouyou')
        .toList();

    // Separate unmuted and muted streams
    var unmutedAlVideoStreams = alVideoStreams.where((obj) {
      var participant = refParticipants.firstWhere(
          (p) => p.videoID == obj.producerId,
          orElse: () => Participant(
              name: 'none', videoID: '', audioID: '', muted: false));
      return !obj.muted! &&
          participant.muted == false &&
          (participant.name != 'none');
    }).toList();

    var mutedAlVideoStreams = alVideoStreams.where((obj) {
      var participant = refParticipants.firstWhere(
          (p) => p.videoID == obj.producerId,
          orElse: () => Participant(
              name: 'none', videoID: '', audioID: '', muted: false));
      return obj.muted! ||
          (participant.name != 'none' && participant.muted == true);
    }).toList();

    // Add unmutedAlVideoStreams to mixedStreams
    mixedStreams.addAll(unmutedAlVideoStreams);

    // Interleave the mutedAlVideoStreams and nonAlVideoStreams
    var nonAlIndex = 0;
    for (var i = 0; i < mutedAlVideoStreams.length; i++) {
      if (nonAlIndex < nonAlVideoStreams.length) {
        mixedStreams.add(nonAlVideoStreams[nonAlIndex]);
        nonAlIndex++;
      }
      mixedStreams.add(mutedAlVideoStreams[i]);
    }

    // Add any remaining nonAlVideoStreams
    mixedStreams.addAll(nonAlVideoStreams.sublist(nonAlIndex));

    // Insert 'youyou' or 'youyouyou' stream at the start
    if (youyouStream.producerId.isNotEmpty) {
      mixedStreams.insert(0, youyouStream);
    }

    return mixedStreams;
  } catch (error) {
    if (kDebugMode) {
      print('Error mixing streams: ${error.toString()}');
    }
    rethrow;
  }
}