DVR recording a streaming coming from CDN

Wowza Streaming Engine
1

Hi there … I’m trying to record into Wowza DVR a live rtmp stream I’m pulling from Akamai (my source and Wowza corporate distribution connection have a big delay and was causing a lot of buffering and delay, so I’m trying to send it over CDN)

I’m actually able to repeat the stream live on Wowza. I’ve watched the stream for like an hour as a live stream with no problem while DVR is recording (http://wowzaip:1935/dvr/akamai.stream/manifest.f4m)

Now, the DVR recording is all full of gaps if I try to playback the same period I watched live (http://wowzaip:1935/dvr/akamai.stream/manifest.f4m?DVR)

On the logs, I can see a lot of following errors

WARN server comment - DvrStreamStoreBase.storeChunks[dvr/definst/akamai.stream/r

tmp.stream.0] : Skipping chunk. A/V packet times differ by 2613 ms, more than al

lowed 2000 ms. aTime=212992 vTime=210379

INFO server comment - LiveStreamDvrRecorder.endChunk[dvr/definst/akamai.stream]:

Skip chunk: a/v/k: packets: 186/149/0 durations: 3969/4972/-1

INFO server comment - DvrStreamStoreBase.storeChunks[dvr/definst/akamai.stream/r

tmp.stream.0] : Resetting dvr time from dvr:64637/pt:195464 to dvr:70070/pt:215

351/utc:1333641507978

WARN server comment - DvrStreamStoreBase.storeChunks[dvr/definst/akamai.stream/r

tmp.stream.0] : Skipping chunk. A/V durations differ by 3030 ms, more than allow

ed 2000 ms. aDuration=8001 vDuration=4971

INFO server comment - LiveStreamDvrRecorder.endChunk[dvr/definst/akamai.stream]:

Skip chunk: a/v/k: packets: 375/149/0 durations: 8001/4971/-1

WARN server comment - DvrStreamStoreBase.storeChunks[dvr/definst/akamai.stream/r

tmp.stream.0] : Skipping chunk. A/V packet times differ by 3699 ms, more than al

lowed 2000 ms. aTime=228992 vTime=225293

INFO server comment - LiveStreamDvrRecorder.endChunk[dvr/definst/akamai.stream]:

Skip chunk: a/v/k: packets: 189/149/0 durations: 4033/4972/-1

WARN server comment - DvrStreamStoreBase.storeChunks[dvr/definst/akamai.stream/r

tmp.stream.0] : Skipping chunk. A/V packet times differ by 2759 ms, more than al

lowed 2000 ms. aTime=233024 vTime=230265

INFO server comment - LiveStreamDvrRecorder.endChunk[dvr/definst/akamai.stream]:

Skip chunk: a/v/k: packets: 189/149/0 durations: 4033/4972/-1

what could be the cause of Wowza not able to record properly? is there a pre-buffering setting I could increase for this?

When I sent to Wowza a stream from my corporate encoder on same LAN, I’ve no problem. Is only when trying to repeat from the CDN. Again, repeating the live has no issues at all.

Thanks for any help

2

hi there … I’m still trying to figure this out … any help? any other approach I could take?

Thanks for any advice

Cheers

3

Hi Lisa, I don’t believe the problem is at the source

As I mentioned on my original post, if I play the live stream as I receive it, there’s no problem at all … it plays perfectly well, no A/V issue

The problem appears when I try to record the live I’m receiving using the DVR

I’ll try to use the traditional recorder API to see if the problem exists on recording that way, or just on DVR. Meanwhile, do you think somethins could be the problem?

4

The “Skipping chunk. A/V packet times differ by [x ms]” message is a warning that the video and audio are out of alignment beyond the default value of 2000 ms. Ideally this problem would be fixed upstream from Wowza nDVR as it relies on the audio and video being aligned. Try to fix it in the source/encoder. If not possible, you can try to compensate for this out of alignment problem by increasing the acceptable delta value using the dvrAllowableAVPacketDelta property described in the Advanced nDVR Configuration Guide. Note that use of this property will not fix the out of alignment problem, but it will try to compensate for it.

-Lisa

5

Wowza nDVR inspects the incoming stream and is reporting what it receives. Typically it is an issue with the source or encode, although that might not be your case… somewhere prior to nDVR the audio and video are becoming out of sync.

-Lisa