问题
I'm trying to read a 16bit 16KHz wav (20 seconds long) from on iOS and perform a fingerprint identification. I tried following the guide "GNSDK-for-Mobile-iOS-Developers-Guide" but it doesn't have an objective-c example on page 53 (only C#). My code reads in the whole file and then writes 2K blocks to the function fingerprintWrite (I've also tried passing a pointer to the whole file). The variable "result' is never set to 1 - indicating insufficient data has been passed - but 20 seconds should be enough, right? Can anyone help? Thanks.
This is what I have done:
NSString *filepath = [[NSBundle mainBundle] pathForResource:@"Human.signed.20s.16bit" ofType:@"raw"];
NSData *audioData= [NSData dataWithContentsOfFile:filepath];
BOOL result;
if (error)
NSLog(@"Error reading file: %@", error.localizedDescription);
// for debugging...
NSLog(@"contents: %@", audioData);
NSLog(@"Done:");
unsigned char buffer[audioData.length];
[audioData getBytes:buffer length:audioData.length];
for (int i = 0; i < audioData.length; i++) {
printf("0x%02x ",(unsigned char)buffer[i]);
}
[self.gnMusicIDFileInfo fingerprintBegin:16000 audioSampleSize:16 audioChannels:1 error:&error];
if (error) {
NSLog(@"Error = %@", [error localizedDescription]);
}
int count = 0;
result = 0;
while (result==0 && count<sizeof(buffer)-2048)
{
result = [self.gnMusicIDFileInfo fingerprintWrite:&buffer[count] audioDataSize:2048 error:&error];
NSLog(@"Count = %i",count);
count=count+2048;
}
NSLog(@"result = %i", result);
if (error) {
NSLog(@"Error = %@", [error localizedDescription]);
}
[self.gnMusicIDFileInfo fingerprintEnd:&error];
if (error) {
NSLog(@"Error = %@", [error localizedDescription]);
}
[self.gnMusicIDFileInfo fingerprint:&error];
if (error) {
NSLog(@"Error = %@", [error localizedDescription]);
}
回答1:
20 seconds may not be enough because the identification process requires enough amount of "usable" audio to proceed. Also, when doing a MusicID File identification, it is required to have the audio file from the beginning of a song. If your use case provides only part of a song and the song does not start from the beginning, it will most likely not work. You will need to use MusicID Stream instead.
来源：https://stackoverflow.com/questions/35436280/using-gracenote-sdk-gnsdk-to-read-a-file-and-perform-a-fingerprint-recognition