Re: Converting a QT audio importer to a CoreAudio codec - where to start?
Re: Converting a QT audio importer to a CoreAudio codec - where to start?
- Subject: Re: Converting a QT audio importer to a CoreAudio codec - where to start?
- From: Dave Camp <email@hidden>
- Date: Fri, 27 Jan 2006 14:05:49 -0800
I've taken the sample project, tossed all the IMA and SMAC stuff, and
installed a do-nothing decoder class as a subclass of ACSimpleCodec.
When I load a QuickTime file with my audio type (WMA2), I can see
that my class is loaded and run with some printfs to the console. So
far so good.
However, I don't seem to get any audio data from Core Audio. Here is
my debug log:
WMA2Codec::WMA2Codec
WMA2Codec::GetPropertyInfo - property:of4i size: 40, writable: false
WMA2Codec::GetProperty - kAudioCodecOutputFormatsForInputFormat
mSampleRate: 0.000000
Input Format -
mSampleRate: 22050.000000
mFormatID: WMA2
mFormatFlags: 0x00000000
mBytesPerPacket: 0
mFramesPerPacket: 0
mBytesPerFrame: 0
mChannelsPerFrame: 1
mBitsPerChannel: 0
mReserved: 0x00000000
Output Format -
mFormatID: lpcm
mFormatFlags: 0x0000000e
mBytesPerPacket: 0
mFramesPerPacket: 1
mBytesPerFrame: 0
mChannelsPerFrame: 0
mBitsPerChannel: 16
mReserved: 0x00000001
WMA2Codec::GetProperty - kAudioCodecPropertyIsInitialized false
WMA2Codec::Initialize
WMA2Codec::Uninitialize
WMA2Codec::~WMA2Codec
WMA2Codec::WMA2Codec
WMA2Codec::GetProperty - kAudioCodecPropertyIsInitialized false
WMA2Codec::Initialize
WMA2Codec::GetProperty - kAudioCodecPropertyCurrentInputFormat
mSampleRate: 22050.000000
mFormatID: WMA2
mFormatFlags: 0x00000000
mBytesPerPacket: 0
mFramesPerPacket: 0
mBytesPerFrame: 0
mChannelsPerFrame: 1
mBitsPerChannel: 0
mReserved: 0x00000000
WMA2Codec::GetProperty - kAudioCodecPropertyCurrentOutputFormat
mSampleRate: 22050.000000
mFormatID: lpcm
mFormatFlags: 0x0000000e
mBytesPerPacket: 2
mFramesPerPacket: 1
mBytesPerFrame: 2
mChannelsPerFrame: 1
mBitsPerChannel: 16
mReserved: 0x00000001
WMA2Codec::GetProperty - kAudioCodecPropertyRequiresPacketDescription
false
WMA2Codec::GetProperty - kAudioCodecPropertyInputBufferSize 8192
As I mentioned, the class is just a stub at the moment. It just logs
the calls I'm getting and fills the audio output buffers with zeros
(if Core Audio would call me). I wanted to understand the mechanics
of getting a basic decoder running before dragging in actual decoder
source. The code fills in one input format and one output format in
the constructor.
Although QT appears to be playing my file (which it won't do if I
remove my component), my ProduceOutputPackets method is never called.
I also checked AppendInputData and it's not being called either.
Any thoughts as to why I'm not getting any data? Have I filled out
one of the properties incorrectly?
Also, I can't seem to stop at any breakpoints. I set QT Player as the
executable, but I never hit anything...
Thanks,
Dave
On Jan 27, 2006, at 12:03 PM, William Stewart wrote:
The CoreAudio SDK has an example Audio Codec component - This is
installed with the latest XCode Dev tools in /Developer/Examples/
CoreAudio/
There have been some discussions here about the process involved in
doing that, but nothing too detailed.. If you need some help feel
free to ask on this list.
Bill
On 26/01/2006, at 6:01 PM, Dave Camp wrote:
I've been tasked with converting a QuickTime audio decoder
component into a new Core Audio decoder to work around some issues
with QuickTime on Intel. I've read the CoreAudio PDF file from the
developer site and looked through the generic parts of the sample
codec in the SDK.
Does anyone have any tips or pointers on what the shortest way to
move my code into the new component format? One of the QuickTime
engineers suggested this had been discussed on this list before,
but I didn't see anything obvious in the archives.
Thanks,
Dave
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