Wednesday, February 26, 2014
Are android play audio data flows through the ordinary telephone when software layer? Can be modified?
When playing android voip phones, voice data stream is certainly flowing software layers. However, when playing an ordinary telephone, RIL made only to the GSM module AT commands. As voice and data calls, it does not seem to go through RIL. I now want to play regular phone android voice data when encrypted, and therefore must be intercepted voice data, put it back after encryption.
Hope experts can answer the following questions, thank you very much:
1, android playing an ordinary telephone, audio data does not flow through any part of the android software layer it? In other words, during the call voice from MIC, the GSM module, air transport, to each other's GSM module, to the other side of the microphone. Throughout the process, the call sound flow produced no contact android software layers? But from the hardware directly to the hardware?
2, android not have an audio portion of it? It stands to reason any sound input, output, fishes do not have to flow through the audio? Is it time to call an exception?
3, android system also has telephone recording software, if the phone call does not flow through the voice software layer, then how could use the software to record?
4, there are some calls on android background setting software, answer the phone, automatically play a predetermined noise. Call noise simulation scenarios, such as: conferences, dinners, on the road, in the rain, the airport, watching the game, concerts and more. Well, this is not meant to sound data calls only when passing through the android software layer, and can also be modified in the program?<-! Main posts under Banner (D4) -><-! Posts under the main text (D5) ->
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Temporarily not possible
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Thanks for replying, can say that some of the details of it. Feasible means of ordinary telephone audio data can not be intercepted and modified software layer it? If so, can you say why not feasible? Is not the reason that I mentioned above: " call audio stream generated no contact android software layer, but directly from the hardware to hardware "?
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I understand the following, not necessarily correct for reference purposes only.
Voice coding should be able to get before, coding is done by the hardware, and later coded only to RIL.
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Voice during a call from the MIC, the GSM module, air transport, to each other's GSM module, to the other side of the microphone.
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That there should be a section in the middle, between MIC / microphone and GSM, there should be a process of decoding ed. If you need to intercept voice data, it should be in this part of the MIC received voice to do it.
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Thank you for your reply. But to answer the content view, you mean: There codec process between mic and gsm, and therefore can be intercepted in the middle , but above you and say, encoding hardware to do . That still did not go through the whole process of software layers Yeah, that how intercept it?
You mentioned data stream codec added after the process is as follows:
MIC (hardware) -> coding (hardware) -> GSM module (hardware) -> Air transport (hardware) -> other GSM module (hardware) -> the other side of the microphone (hardware)
You can see the whole process seems that hardware at work, ah, there is no flow through the android software layer, and therefore can not intercept?
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After MIC hardware is to lead the software. At least by driving it.
May also pass more upper management software. But I am not sure which module corresponds Android.
Then processed by software, which application should go to. I think you should be here on the intercepted data.
If this is a voice call, the next code will go.
Encoding is not necessarily the hardware, it may be software.
From the beginning of the encoding process is estimated bad insert your own code.
You are in the process of painting the hardware, but the hardware is also controlled by the software, you can check the android hardware associated with these API look.
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MediaRecorder recorder = new MediaRecorder ();
recorder.setAudioSource (MediaRecorder.AudioSource.VOICE_CALL);
You can record a voice call down the line ports
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Learn
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You can record it should be no problem, but it does not call for the original voice data to change it. Recording only the equivalent of a copy, but if you want to call voice encryption, then it must have the ability to alter the original voice calls.
If you just recorded, then the equivalent of intercepted voice, but still no way to put it back after it is modified.
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I also encountered a similar problem with lz, want an autoresponder software, but do not know how to send a prerecorded audio each other, such as "Please leave a message after hearing the D sound." Personal imagined solution is to play the sound output is set to mic, so you can hear the other party, expert guidance
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This solution enables you.
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You can put your voice to be played through the speakers play out, and then it can be collected to MIC
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The landlord did not solve? I also encountered this problem, the landlord pointing to pointing it! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
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I do not know what LZ is used GSM program, brother happens to be driven to do this voice modem, and also a lot of contact with AP, said little things right:
MIC from the AP to the side of the CODEC chip mining, connected directly through PCM interface and modem chips, and AP Andrews did not need any relationship side, the side to get the modem to the PCM data mining will have its own speech enhancement, encoding process , then to the physical layer to the empty
Before also done voice encryption solution, typically to provide an external encryption library, and then taken to the PCM data modem after the speech enhancement, encoding, and then call interface is encrypted, and then sent to the physical layer to the empty
This fact together voice calls and the AP side nothing, AP side only controls the codec chip, nothing else to do
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Thank you, that is, to call this thing, android is only responsible for sending control commands (such as call AT commands), but the process to achieve the caller, not the android thing, but the modem things, the equivalent android just notice modem: Dude, make a phone call. As for the specific call, it took over responsibility from the modem, and android lacks relationship. It is good to understand, in the absence of the era of smart phones and android phone is not still playing it, as long as the phone's modem has become.
So, in this case, the need for ordinary telephone voice encryption android phone, it is necessary to obtain the baseband source (and can be programmed into the machine after successfully modified), because the modem baseband is software that can be understood?
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Agreed to the 13th floor view. In general, the call when data has nothing to do with the AP, MIC data from the hardware path to direct Modem; But you can also change the VOICE CALL path, let MIC data to AP, and then from the AP to encrypt Modem, which need your codec support, so the estimated delay is relatively large, but not universal platform. If the modem side can cut, or do the modem end encryption is reasonable.
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With the idea of seeking ah. . . . . . . . . . . .
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This problem has not been resolved ah?
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When you call, the data coming from the Modem, if modem using PCM mode, the data is sent via PCM audio codec, codec and then decode and then select the playback path is completed in the kernel. Without android. Modem to the codec, but the digital signal is transmitted.
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