nDVR with alternate audio

Wowza Streaming Engine
1

Hi,

is it possible to use nDVR for streams with alternate audio tracks? If so, is the streams and smil configuration the same as for simple live streaming?

thanks

2

Hey that’s a great question @Michal Vanco, I did check for you and yes you would set up the alternate audio tracks the same way you would now in a SMIL file and this will work for the nDVR.

Important:

For everything to be synchronized, the alternative tracks must be timecode-aligned. This means that they must come from the same encoder or from separate encoders that produce aligned streams.

HLS:

https://www.wowza.com/docs/how-to-use-alternative-audio-or-video-tracks-with-apple-hls-streams

MPEG-DASH:

https://www.wowza.com/docs/how-to-use-alternative-audio-or-video-tracks-with-mpeg-dash-streams

3

Thank you for you response.

I have my alternate audio stream working for live streaming (cupertino). But it doesn’t work with nDVR. I see console log full of:

2019-10-31 06:40:36 WARN server comment - DvrPacketHandler.handleHolder[live/_definst_/mystream_vid_l1.stream] Over flush iteration limit.
2019-10-31 06:40:36 WARN server comment - LiveStreamPacketizerCupertino.handleHolder[live/_definst_/mystream_vid_l1.stream]: chunkLastAudioTimecode:-1 chunkHitEndKeyTimecode:24139562 chunkStartTimecode:24139642 chunkStartTimecodePTS:24139642 chunkHitEndKey:true chunkCodecInfoAudio:null chunkCodecInfoAudioSent:false chunkCodecInfoVideo:{MediaCodecInfoVideo: codec:H264, profile:High, level:4.1, frameSize:1920x1080, displaySize:1920x1080, frameRate:25.000000} chunkCodecInfoVideoSent:false chunkKeyCount:1 chunkAudioCount:0 chunkAudioInARowCount:0 chunkAudioDuration:0

When I try to play the nDVR stream (with the ?DVR query parameter) I see this:

2019-10-31 06:43:40 WARN server comment - DvrMbrAlignmentResolver.getChunksSpans[mystream_vid_l5.stream.0]: null entry: first:null last:null
2019-10-31 06:43:40 WARN server comment - DvrMbrAlignmentResolver.getChunksSpans[mystream_vid_l4.stream.0]: null entry: first:null last:null
2019-10-31 06:43:40 WARN server comment - DvrMbrAlignmentResolver.getChunksSpans[mystream_vid_l3.stream.0]: null entry: first:null last:null
2019-10-31 06:43:40 WARN server comment - DvrMbrAlignmentResolver.getChunksSpans[mystream_vid_l2.stream.0]: null entry: first:null last:null
2019-10-31 06:43:40 WARN server comment - DvrMbrAlignmentResolver.getChunksSpans[mystream_vid_l1.stream.0]: null entry: first:null last:null

Any clues?

Thanks

4

I’m not 100% sure why from what you have shared @Michal Vanco and the engineers can only debug in a support ticket. Can you submit one here and tech support will see what is the issue here.

I’m guessing the Cupertino packets are not aligned properly as far as keyframes and timestamps which is critical to smooth switching.

Or it could be it requires additional configuration for the nDVR that I am not familiar with. With a support ticket, the engineers will quickly be able to identify and correct it.

5

I will try to open a support ticket then. Thanks for you answer.