Wowza Community

Transcoder addon AAC LATM, does wowza support this codec for transcoding

Hi Guys,

I am having problem transcoding a stream with aac latm as audio. HLS streams comes out without audio.

2013-10-02	05:29:46	ECT	comment	server	INFO	200	-	LiveStreamPacketizerCupertino.handlePacket[SVorigin/_definst_/430]: Video codec:H264 isCompatible:true	-	-	-	4.662	-	-	-	-	-	-	-	-	-	-	--	-	-	-	-	-	-	-	-	-	-	-	-	-
2013-10-02	05:29:46	ECT	comment	server	INFO	200	-	LiveStreamPacketizerCupertino.handlePacket[SVorigin/_definst_/430]: Audio codec:AAC isCompatible:true	-	-	-	4.663	-	-	-	-	-	-	-	-	-	-	-	--	-	-	-	-	-	-	-	-	-	-	-	-
LiveStreamPacketizerCupertino.endChunkTS[SVorigin/_definst_/430]: Add chunk: id:5 mode:TS[H264,AAC] a/v/k:0/351/24 duration:11712
INFO server comment - LiveStreamPacketizerCupertino.endChunkTS[SVorigin/_definst_/430_360p]: Add chunk: id:4 mode:TS[H264,NOAUDIO] a/v/k:0/360/3 duration:12012
INFO server comment - LiveStreamPacketizerCupertino.endChunkTS[SVorigin/_definst_/430_3602p]: Add chunk: id:4 mode:TS[H264,NOAUDIO] a/v/k:0/360/3 duration:12012
INFO server comment - LiveStreamPacketizerCupertino.endChunkTS[SVorigin/_definst_/430_720p]: Add chunk: id:4 mode:TS[H264,NOAUDIO] a/v/k:0/360/3 duration:12012

Does wowza support this AAC format?

Regards,

Hi,

Yes, Wowza supports AAC audio. The issue here is that Wowza is not receiving audio packets from the source. Perhaps there is an issue with your encoder configuration?

-Tim

What is the source? I think Tim’s first suggestion was going in the right direction: Wowza is not getting the audio from the source. The packetizing method is for the outgoing stream rtsp stream.

Does the un-transcoded stream from Wowza playback in Flash RTMP client? Does it playback in VLC over RTSP? What do you see in VLC Tools > Codec info? And can you play the source in VLC, and what does Tools > Codec info say in that case?

Richard

Isaac, and Yee,

We would need to take a closer look, and need access to the source, or a recording of it. Open a ticket by writing to support@wowza.com. Include a link to thread for reference.

Richard

We’ll have to take a closer look. Restart Wowza and test through to replicate, then zip up and send /conf and current access log showing restart and testing to support@wowza.com

Richard

I have the same problem as Ferdinand has.

Our source is multicast UDP MPEG-TS H264 + AAC-LATM (source is DVB-T).

This is the logs:

JNI:AudioDecoderAAC.decodeFirstFrame[_defaultVHost_:live/_definst_/m3.stream]: Decode failed

If you need more information I can provide.

It takes a while until I able to reproduce successfully the issue but now everything is clear.

Here are the findings:

If the source is AAC LATM and the AAC’s SRB extension is used -> no sound and Decode failed message is appears in the log

If the source is AAC LATM and NO SRB is used -> NO sound and NO error message in the log

Edit: mail sent to support

I’ve opened ticket with the support and wowza does not support LATM for decoding.

That’s the official answer from support:

Currently we do not support input with no ADTS headers. We can provide an output for RTP but not the input. I will get this added to our feature request list but at the moment it is not supported.

As a workaround use ffmpeg for transcoding audio and passthru the video.

I’m using this simple script for transcoding audio (this is a windows batch file, but you can easily convert to bash):

:start
c:\ffmpeg\ffmpeg-2.2.1-x64\ffmpeg.exe -i udp://239.123.13.155:58155?fifo_size=334651^&overrun_nonfatal=1^&buffer_size=9175040 -map #0xc3b  -c:v copy -strict experimental -map #0xc3c -c:a aac -b:a 192k -f mpegts -mpegts_flags resend_headers udp://127.0.0.1:58011?pkt_size=1316^&reuse=1
echo Restart at: %date% %time% >>c:\ffmpeg\restart.log
timeout /T 5
goto start

Hi all,

We are having exactly the same issue with exactly the same setup (HD stream from satellite).

Did anyone manage to fix this issue?

Our exact stream details from the sat feed are (from ffprobe):

Stream #0:0[0xc9]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc

Stream #0:10xca: Audio: aac_latm ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp

Video is being transcoded with no issue but audio is having issues to be decoded.

Thx,

Isaac.

Hello,

Any updates on this? I’m having a similar issue with Wowza 3.6.4 and following audio codec based on VLC information:

Codec: A52 Audio (aka AC3)(a52)

Original ID: 572

Channels: Stereo

Sample rate: 48000 Hz

Bitrate: 256 kb/s

I’ve tried setting the following properties in RTP section of application.xml but no luck:

audioPacketizerAAC

com.wowza.wms.rtp.packetizer.RTPPacketizerMPEG4LATM

mpegtsImportAC3

true

Boolean

audioIsAligned

false

Boolean

Video and audio play fine in VLC but Wowza transcoder can not decode the audio. Many HD dvb channels use mpeg4 audio and not sure about transcoder support at this point.

As a follow up, I see that you are using mp4a-latm packetization. Take a look at this property which should resolve the issue: Property to change AAC packetization method:

Wowza Media Server can output AAC audio using the mpeg4-generic and mp4a-latm (3gpp) packetization methods. The default packetization method is mpeg4-generic. To switch to mp4a-latm (3gpp), add the following property to the RTP/Properties container in [install-dir]/[application]/Application.xml (be sure to get the correct container, there are several in the Application.xml file):

<Property>
    <Name>audioPacketizerAAC</Name>
    <Value>com.wowza.wms.rtp.packetizer.RTPPacketizerMPEG4LATM</Value>
</Property>

-Tim

Hi Tim,

Thanks for the reply, I have already set this audioPacketizerAAC property just to check if it might solve the problem we are having but the problem still exist. The streams are coming from SAT and being encapsulated into IP Multicast by our IRD as input for wowza, the format is mpeg ts SPTS. I have tried playing the streams coming from the IRD using vls and it recognized the audio without a problem.

The streams might not be properly aligned but according to the changes in 3.6.2 patch 12, mpegtsVideoIsAligned and mpegtsAudioIsAligned are set to false by default. We are also transcoding this stream using wowza transcoder.

I found this logs on the server:

INFO server comment - JNI:TranscoderSession.audioDecoderCreate[_defaultVHost_:SVorigin/_definst_/430]: Create audio decoder: AAC: default
INFO transcoder decoder-audio-start 430 {codec:AAC, objectType:SBR, sampleRate:44100, channels:2}
INFO server comment - JNI:TranscoderSession.audioEncoderAdd[_defaultVHost_:SVorigin/_definst_/430:360p]: Create audio encoder: AAC: default
INFO server comment - JNI:TranscoderSession.audioEncoderAdd[_defaultVHost_:SVorigin/_definst_/430:720p]: Create audio encoder: AAC: default
WARN server comment - JNI:AudioDecoderAAC.decodeFirstFrame[_defaultVHost_:SVorigin/_definst_/430]: Decode failed
WARN server comment - TranscoderWorkerAudioDecoder.handlePacket: Error audioDecoderDecodeFirstFrame: 4294967295

Somehow it’s failing to decode the audio streams

Regards,

anyone?

Hi Richard,

Sorry for not being able to reply to the thread and for reviving it, we’ve been very occupied lately. We are still having this issues on some of out clients. It seems like Wowza fails to decode all the streams that has AAC-HE and AAC-LATM, so the HLS output will have no audio.

I saw that there a few here who are experiencing the same issue. Was there any solution? Can it be posted here on the forum, please? We mostly have this problem on latin american channels which will most of the time have AAC-HE and AAC-LATM.

Regards,

Feridnand

As a follow up, I see that you are using mp4a-latm packetization. Take a look at this property which should resolve the issue: Property to change AAC packetization method:

Wowza Media Server can output AAC audio using the mpeg4-generic and mp4a-latm (3gpp) packetization methods. The default packetization method is mpeg4-generic. To switch to mp4a-latm (3gpp), add the following property to the RTP/Properties container in [install-dir]/[application]/Application.xml (be sure to get the correct container, there are several in the Application.xml file):

<Property>
    <Name>audioPacketizerAAC</Name>
    <Value>com.wowza.wms.rtp.packetizer.RTPPacketizerMPEG4LATM</Value>
</Property>

-Tim

Wowza will only pass thru AC3 for HLS and Smooth clients. Wowza Transcoder does not support ac3 for decode or encode.

Salvadore

Thank you for sharing your findings. And welcome to the wowza support forum.

Best,

Salvadore

We face similar problem

in our scenario we have H.264/AAC source channel comming from SAT. we stream this channel via our IRD (dvblast) as a source for wowza.

Signal -> IRD -> MPEGTS over udp -> wowza

VLC show that audio codec is mp4a

ffmpeg show that audio codec is latm_AAC

wowza logs show thar audio codec is AAC

VLC can play video and audio (everything is OK)

but after wowza we have no audio. either using transcoder or not (pass-through audio).

depacketization which is used by wowza is : MPEGTSDepacketizer which detect audio stream and show audio stream id (PID) properly.

we are doubtful to aac_latm in audio source. another clue to this is when our input channel audio has not latm filter and it is pure AAC everything works fine.

maybe wowza didn’t use appropriate depakcetizer for MPEGTS udp input stream.

would you please help us

Hi

we face similar problem too.

when incoming signal (from SAT) uses aac_latm for its audio we get no audio after wowza, either using transcoder or not.

the scenario is described here:

Signal from SAT -> IRD -> MPEG-TS over udp -> wowza -> restream (with transcode) to other formats.

MPEG_TS stream before wowza is playable in VLC and audio codec is mp4a (video codec is H.264)

also with from ffmpeg we know that audio codec is latm_aac

we are doubtful of latm filter, because when incoming audio is pure aac whole scenario works perfectly.

it is not matter of Packetizer it is about DePacketizer (for incoming stream)

also another usefull information is that in wowza detect an AAC stream and use MPEGTS DePacketizer for that.

but maybe there should be an AACLATMDePacketizer or MP4ADePacketizer in wowza for this kind of audio stream.

Isaac, and Yee,

We would need to take a closer look, and need access to the source, or a recording of it. Open a ticket by writing to support@wowza.com. Include a link to thread for reference.

Richard

Hi Richard

but i already had opened an issue for this (ticket #70272) and uploaded a small sample of incoming video for that.

and the final result as Roger said is:

“The stream is missing ADTS Headers on the audio stream. Without these headers, Wowza is unable to process the stream properly.”

more detailed information are available in this http://www.wowza.com/forums/showthread.php?33951-LATM-DePacketizer-problem

i hope this helps and wowza will support this kind of stream in near future.

Hi,

I have the same problem, trying to transcode and stream an Israel DVB-T stream received from dvblast.

Ofer