Re: shoutcast stream encoding debug
Re: shoutcast stream encoding debug
- Subject: Re: shoutcast stream encoding debug
- From: Eric Allamanche <email@hidden>
- Date: Mon, 4 Apr 2011 10:32:01 -0700
On Apr 2, 2011, at 2:13 PM, Ethan Funk wrote:
> VLC wont play it either, and iTunes does (as of some recent version) play aac+ streams... works fine when I send the data encoded with the aacplusenc program, it just won't play it when I use the CoreAudio encoder and with my ADTS packet headers.
>
> Unless I am incorrect that what is commonly called "aacplus" is actually AAC-HEv1 and "aacplusv2" is AAC-HEv2. If I am wrong, then what is aacplusenc actually doing? Either the CoreAudio AAC-HE coder is doing something different that aacplusenc or my ADTS header is wrong for AAC-HE packets, but correct for AAC-LC. And I'd bet on it being my error someplace.
Have you verified that the information you're embedding in your ADTS header relates to the AAC-LC core layer and not to the HE extension layer? Here's an example of the different layers of an HE-v2 stream:
- AAC-LC: 220.25kHz, 1 channel ('aac ')
- AAC-HEv1: 44.1kHz, 1 channel ('aach')
- AAC-HEv2: 44.1kHz, 2 channel ('aacp')
Since the ADTS header only describes the LC layer, according to this example, you need to set the sample rate to 22.025kHz and the channel configuration to 1.
Eric
>
> Ethan...
>
> On Apr 2, 2011, at 1:52 PM, Kyle Sluder wrote:
>
>> On Apr 2, 2011, at 1:29 PM, Ethan Funk <email@hidden> wrote:
>>
>>> I have aac-lc working... forgot to send packets using ADST headers, as required by shoutcast protocol for aac format. Now to figure out why aac-he still doesn't play, even with ADTS headers.
>>
>> IIRC iTunes just doesn't play HE-AAC. We had this problem a few years ago when we wanted to stream our station using Orban's HE-AAC encoder. Not much point in doing so if the most common media player won't decode the stream.
>>
>> Perhaps a newer version of iTunes has changed that behavior.
>>
>> --Kyle Sluder
>
>
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