# AAC streaming problem **URL:** \ **Category:** Wowza Streaming Engine\ **Created:** [June 29, 2010, 10:17am UTC](https://community.wowza.com/t/aac-streaming-problem/34022 "2010-06-29T10:17:18Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Leo\_Wang](https://avatars.discourse-cdn.com/v4/letter/l/c37758/32.png) [@Leo\_Wang](https://community.wowza.com/u/Leo_Wang)\ **Post date:** [June 29, 2010, 10:17am UTC](https://community.wowza.com/t/aac-streaming-problem/34022/1 "2010-06-29T10:17:18Z")
I observed that in some rare cases, when I use jwplayer to play a recorded stream, I cannot hear any sound. So I grabbed the archived file and use ffprobe to analyze the file: ```auto ~$ ffprobe temp.flv FFprobe version SVN-r23840, Copyright (c) 2007-2010 the FFmpeg developers ... libavutil 50.19. 0 / 50.19. 0 libavcodec 52.78. 0 / 52.78. 0 libavformat 52.71. 0 / 52.71. 0 libavdevice 52. 2. 0 / 52. 2. 0 libavfilter 1.20. 1 / 1.20. 1 libswscale 0.11. 0 / 0.11. 0 [aac @ 0x101012e00] channel element 1.0 is not allocated Last message repeated 8656 times [flv @ 0x101011c00] Estimating duration from bitrate, this may be inaccurate Input #0, flv, from 'temp.flv': ``` The file is playable in mplayer despite of the following messages: ```auto [aac @ 0x10186d200] channel element 1.0 is not allocated Last message repeated 8656 times [flv @ 0x102010c00] Estimating duration from bitrate, this may be inaccurate [lavf] stream 0: video (h264), -vid 0 [lavf] stream 1: audio (aac), -aid 0 VIDEO: [H264] 320x240 0bpp 15.000 fps 0.0 kbps ( 0.0 kbyte/s) Clip info: duration: 0 creationdate: Fri Jun 25 14:27:46 ========================================================================== Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264) ========================================================================== ========================================================================== Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding) Unsupported LATM configuration: 1 programs/ 2 subframes, 3 layers, allstreams: 1 versionA not supported versionA not supported Unsupported LATM configuration: 1 programs/ 2 subframes, 3 layers, allstreams: 1 versionA not supported versionA not supported ``` I then manually parsed the flv file, I found the AAC header packet is missing. In the other word, ```auto faacEncGetDecoderSpecificInfo(hEncoder, &extra, &extra_size); ``` the “extra\_size” octets in “extra” are missing. It is usually the first audio packet sent through RTMP audio channel, but due to some unknown reason, it is lost. That’s why Flash Player cannot play it: it failed to recognize the information required to decode it. It is quite hard to reproduce the problem. wowza is set up on my localhost, so I don’t think it is network-latency-related. Is it possible for wowza to provide a valid AAC header when it does not exist? Thanks. ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [June 29, 2010, 9:54am UTC](https://community.wowza.com/t/aac-streaming-problem/34022/2 "2010-06-29T09:54:15Z")
I don’t really understand the question. Charlie ---
**Author:** ![Richard\_Lanham](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@Richard\_Lanham](https://community.wowza.com/u/Richard_Lanham)\ **Post date:** [June 29, 2010, 2:20am UTC](https://community.wowza.com/t/aac-streaming-problem/34022/3 "2010-06-29T02:20:14Z")
No, Wowza is just going to record what it gets. Richard ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [June 29, 2010, 3:23am UTC](https://community.wowza.com/t/aac-streaming-problem/34022/4 "2010-06-29T03:23:09Z")
I kind of understand the issue. What encoder are you using? In general if using an RTSP/RTP encoder then we extract this information from the SDP data that is exchanged. I have not heard of others with this issue. Not sure why you are seeing it. I would need to reproduce it to have a chance of understanding it. Charlie ---
**Author:** ![Richard\_Lanham](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@Richard\_Lanham](https://community.wowza.com/u/Richard_Lanham)\ **Post date:** [September 23, 2013, 1:50pm UTC](https://community.wowza.com/t/aac-streaming-problem/34022/5 "2013-09-23T13:50:08Z")
[duplicate](https://www.wowza.com/forums/showthread.php?1147-Live-streaming-with-RTP-RTSP-source-and-LATM) ---
**Author:** ![Leo\_Wang](https://avatars.discourse-cdn.com/v4/letter/l/c37758/32.png) [@Leo\_Wang](https://community.wowza.com/u/Leo_Wang)\ **Post date:** [June 29, 2010, 11:55am UTC](https://community.wowza.com/t/aac-streaming-problem/34022/6 "2010-06-29T11:55:55Z")
> No, Wowza is just going to record what it gets. > > Richard What is the logic of live-streaming a file which contains valid AAC header? First, wowza sends the AAC header packet to make it possible for the player recognize the audio format, then, sends the audio data part. Is it correct? The problem is very hard to reproduce, but it does happens occasionally, what should I do for a workaround? If I patch the recorded file on-the-fly, will it also help for _live_ streaming? Thanks. ---
**Author:** ![Leo\_Wang](https://avatars.discourse-cdn.com/v4/letter/l/c37758/32.png) [@Leo\_Wang](https://community.wowza.com/u/Leo_Wang)\ **Post date:** [June 30, 2010, 1:37am UTC](https://community.wowza.com/t/aac-streaming-problem/34022/7 "2010-06-30T01:37:24Z")
I use FMLE to push rtmp stream to wowza. It seems that sometimes the first audio packet (header) is missing, but _never_ has been the video header packet. It is very hard to reproduce, so I think maybe I have to find a workaround. For a recorded live stream, does wowza fetch the audio header from the recorded file or just use a header in memory? Thanks. ---
**Author:** ![yee\_woon](https://avatars.discourse-cdn.com/v4/letter/y/439d5e/32.png) [@yee\_woon](https://community.wowza.com/u/yee_woon)\ **Post date:** [September 21, 2013, 3:28am UTC](https://community.wowza.com/t/aac-streaming-problem/34022/8 "2013-09-21T03:28:25Z")
Is it possible to re-stream a stream with H.264 video and “ffmpeg aac in latm” audio codec (as mplayer recognized) in Wowza? If yes, could you please say how? I tried It by using “AAC” codec in transcoder file and default audio packetizer and also several scenarios that have been explained in Wowza documentations, but i couldn’t get any audio in my (for example rtmp) output stream and also VLC is unable to play the whole stream (I mean no audio and no video displayed!).