Re: Conversion to 3gp
Re: Conversion to 3gp
- Subject: Re: Conversion to 3gp
- From: William Stewart <email@hidden>
- Date: Thu, 19 Jul 2007 17:28:09 -0700
On 19/07/2007, at 2:50 PM, Norman Franke wrote:
Seems I was mistaken. I don't think the iPhone supports .3gp AMR,
just .3gp AAC. This is rather surprising given the painfully slow
EGDE network's capabilities in that it supports no low bitrate
speech formats. So, I guess I'll be converting to AAC, and I assume
I can export .mp4 using a similar method.
One can do this without a temp file using
AudioFileInitializeWithCallbacks?
Sure - audio file supports reading/writing mp4 with AAC on tiger
Bill
-Norman
Quoting William Stewart <email@hidden>:
I can help you on Leopard but not on previous systems, through the
use of the CoreAudio APIs.
On Leopard we will have the ability to write 3gp files with AMR
data. You can use the ExtendedAudioFile API quite simply:
(1) Create an ExtAudioFile object of type 3gp and data format is AMR
(2) Set the client format to a PCM format that is most convenient
to you
(3) Push data in using the ExtAudioFileWrite call, where you
provide it the data in the format you set, and it will handle the
conversion and write to the underlying file object for you.
You could use the ConvertFile example (/Developer/Examples/
CoreAudio) in the SimpleSDK folder as a starting point. You could
for instance, write CAF files with AMR data in it. Then, when you
have Leopard you will be able to write the 3GPP file. On Leopard
as well, you can also read and write AMR files if that's of interest.
Thanks
Bill
On 19/07/2007, at 1:14 PM, Norman Franke wrote:
I'm attempting to convert a custom ADPCM format to 3GP / AMR for
streaming to an iPhone. I need to do this without a GUI,
basically, pass it a buffer of samples and get a .3gp file as
output. I'd prefer to do this without an intermediate file.
I've looked at the same code on apple.com (under QuickTime), most
of which is quite out of date. None seem to do this without a GUI
and/or file IO.
I had some old code that uses SoundConverter to convert to
PureVoice, but I had to hard code the compression params (magic
cookie).
How do I specify both the media type AMR and file type (3gp), get
the magic cookie/compression params and the like?
Is the the wrong way to go?
-Norman
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