Hi
After reading so much on the speak here apple's example, i couldnt understand what parts of it i need .
I only need to always get the audio data from mic , and check the power of it , in order to measure the audio input duration in ms .
I want to get to the place where i can get the audio level and write there my own objective c code, or send it to another .m file of my own.
Can someone direct me to that variable that holdes that data ?
and what are the things i can erase from it? (dont need openGL,quartz,play sounds,and view any graph )
Thanks a lot.
Related
I would like to fill an array from a stream for around ten seconds.{I wish to do some processing on the data)So far I can:
(a) obtain the microphone stream using mediaRecorder
(b) use analyser and analyser.getFloatTimeDomainData(dataArray) to obtain an array but it is size limited to only a little over half a second of data.I can also successfully output the data after processing back onto a stream and to outDestination.
(c) I have also experimented with obtaining a 'chunks' array from mediaRecorder directly but the problem then is that I can't find any mime type that would give me a simple array of values - ie an uncompressed sample by sample single channel set of value - ie a longer version of 'dataArray' in (b).
I am wondering if I am missing a simple way round this problem?
Solutions I have seen tend to use step (b) and do regular polls then reassemble a longer array - however it seems the timing is a bit tricky ..
I'v also seen suggestions to use audio workouts - I might have to do this but would prefer a simpler solution!
Or again, if someone knows how to drive mediaRecorder to output the chunks array in a simple array format FLOAT32.of one channel.That would do the trick.
Or maybe I'm missing something simpler?
I have code showing those steps that have been successful and will upload if anyone requests.
I've been looking around Swift documentation to save an audio output from AVAudioEngine but I couldn't find any useful tip.
Any suggestion?
Solution
I found a way around thanks to matt's answer.
Here a sample code of how to save an audio after passing it through an AVAudioEngine (i think that technically it's before)
newAudio = AVAudioFile(forWriting: newAudio.url, settings: nil, error: NSErrorPointer())
//Your new file on which you want to save some changed audio, and prepared to be bufferd in some new data...
var audioPlayerNode = AVAudioPlayerNode() //or your Time pitch unit if pitch changed
//Now install a Tap on the output bus to "record" the transformed file on a our newAudio file.
audioPlayerNode.installTapOnBus(0, bufferSize: (AVAudioFrameCount(audioPlayer.duration)), format: opffb){
(buffer: AVAudioPCMBuffer!, time: AVAudioTime!) in
if (self.newAudio.length) < (self.audioFile.length){//Let us know when to stop saving the file, otherwise saving infinitely
self.newAudio.writeFromBuffer(buffer, error: NSErrorPointer())//let's write the buffer result into our file
}else{
audioPlayerNode.removeTapOnBus(0)//if we dont remove it, will keep on tapping infinitely
println("Did you like it? Please, vote up for my question")
}
}
Hope this helps !
One issue to solve:
Sometimes, your outputNode is shorter than the input: if you accelerate the time rate by 2, your audio will be 2 times shorter. This is the issue im facing for now since my condition for saving the file is (line 10)
if(newAudio.length) < (self.audioFile.length)//audiofile being the original(long) audio and newAudio being the new changed (shorter) audio.
Any help here?
Yes, it's quite easy. You simply put a tap on a node and save the buffer into a file.
Unfortunately this means you have to play through the node. I was hoping that AVAudioEngine would let me process one sound file into another directly, but apparently that's impossible - you have to play and process in real time.
Offline rendering Worked for me using GenericOutput AudioUnit. Please check this link, I have done mixing two,three audios offline and combine it to a single file. Not the same scenario but it may help you for getting some idea. core audio offline rendering GenericOutput
Hey fellows,
Iam trying to build an application for realtime voicechanging.
In a first step I managed to record audiodata to a specified file and to play it after recording.
Now I try to change the code for playing back the audiobuffers right after recording them in loop.
My question is, how it is possible to read the Audiodata directly from the recording Audioqueue and not (like shown in documentation) from a file.
Iam thankful for any ideas and could show code-parts if needed.
Thanks in advance,
Lukas (from Germany)
Have a look at the SpeakHere example. This line sources the audio data:
OSStatus result = AudioFileReadPackets(THIS->GetAudioFileID(), false, &numBytes, inCompleteAQBuffer->mPacketDescriptions, THIS->GetCurrentPacket(), &nPackets,
inCompleteAQBuffer->mAudioData);
So, rather than call AudioFileReadPackets, you can just use a memcpy to copy over the recorded data buffer. Or, alternatively, supply to the playback AudioQueue a pointer to the audio data buffer. As playback continues, advance a mCurrentPacket pointer through the buffer.
To record, you'll do something very similar. Rather than writing out to a file, you'll write out to a buffer in memory. You'll first need to allocate that with a malloc. Then are your incoming AudioQueue captures recorded data, you copy that data to the buffer. As more data is copied, you advance the recording head, or mCurrentPacket to a new position.
We are seeing this when "tying" two video files together.
Example we have Ad video that is segmented and content file which is also segmented.
We create a new file which has both Ad and content segment information together. However we are seeing an issue where either the Ad content is truncated or the content starts having A/V sync issues.
Both ad and content are segmented the same way , 5 sec segmentation. however since Ads are variable length the result file may have left over segment something like:
#EXTM3U
#EXT-X-TARGETDURATION:5
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:5,
fileSequence6.ts
#EXTINF:5,
fileSequence7.ts
#EXTINF:4,
fileSequence8.ts
#EXTINF:5,
fileSequence0.ts
#EXTINF:5,
fileSequence1.ts
#EXTINF:5,
fileSequence2.ts
#EXTINF:3,
fileSequence3.ts
Is this the proper way to play 2 files one after the other without rebuffering?
should generate-variant-plist be used to a play list of 2 files?
When you have a break in the stream to switch to a commercial, ad, or alternate video source then you want to introduce the discontinuity tag before the start of the next segment, for example:
#EXTM3U
#EXT-X-TARGETDURATION:5
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:5,
movie0.ts
#EXTINF:2,
movie1.ts
#EXT-X-DISCONTINUITY
#EXTINF:5,
commercial0.ts
#EXTINF:5,
commercial1.ts
#EXTINF:3,
commercial2.ts
This gets a little more complicated if you encrypt the streams because they use progressive encryption based on the prior segments encryption state and the sequence number which come together to form an "Initialization Vector". If you break the stream you have to reset the initialization vector so that the encryption/decryption can continue uninterrupted. This is an involved process so best to just search on Initialization Vector in Apple's docs.
I have a 2giga mpeg file of people runnig,jogging,walking etc. in it. I will use it in a image classification project but I need to segmentate the video depending on per person an per action.
for example;
there are 25 people in video which repeat these actions in order
1st person
-runs
-walks
2nd person
-runs
-walks
and goes on....
and what I want is to have 2 different mpeg file for each person
such as;
firstperson_runs.mpeg
firstperson_waves.mpeg
so I need a tool to split big file into these files. Splitting shall be due to time.
such as;
pick t1:start of action
pick t2:end of action
create a new video from big file for the interval t1 and t2
of course I will select time intervals for each video.
OS:Winxp pro
if it can be done by matlab ,can you describe it?
any help???
I imagine there are a number of tools available to do this without MATLAB, but if you really want to use MATLAB I would check out these submissions on The MathWorks File Exchange:
Gerald Dalley's videoIO Toolbox for Matlab
Micah Richert's mmread
David Foti's mpgread and mpgwrite
EDIT:
As mentioned by M456, you can also use the built-in function MMREADER for creating a multimedia reader object for your movie file (and subsequently reading selected movie frames from it with the READ method). However, I don't know which version of MATLAB this function was introduced in. It is in versions 7.7 and 7.8 (R2008b and R2009a, respectively), but it is not in version 7.1.
Matlab can do such video split operations. There are two built in functions (aviread and mmreader) for reading video files. Both will create objects which contain the individual frames of the video. You can save these as separate frames or make a new video out of by using avifile.