1 /* 2 * Copyrightm (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "AudioCodec.h" 18 19 extern "C" { 20 #include "gsm.h" 21 } 22 23 namespace { 24 25 class GsmCodec : public AudioCodec 26 { 27 public: 28 GsmCodec() { 29 mEncode = gsm_create(); 30 mDecode = gsm_create(); 31 } 32 33 ~GsmCodec() { 34 if (mEncode) { 35 gsm_destroy(mEncode); 36 } 37 if (mDecode) { 38 gsm_destroy(mDecode); 39 } 40 } 41 42 int set(int sampleRate, const char */* fmtp */) { 43 return (sampleRate == 8000 && mEncode && mDecode) ? 160 : -1; 44 } 45 46 int encode(void *payload, int16_t *samples); 47 int decode(int16_t *samples, int count, void *payload, int length); 48 49 private: 50 gsm mEncode; 51 gsm mDecode; 52 }; 53 54 int GsmCodec::encode(void *payload, int16_t *samples) 55 { 56 gsm_encode(mEncode, samples, (unsigned char *)payload); 57 return 33; 58 } 59 60 int GsmCodec::decode(int16_t *samples, int count, void *payload, int length) 61 { 62 unsigned char *bytes = (unsigned char *)payload; 63 int n = 0; 64 while (n + 160 <= count && length >= 33 && 65 gsm_decode(mDecode, bytes, &samples[n]) == 0) { 66 n += 160; 67 length -= 33; 68 bytes += 33; 69 } 70 return n; 71 } 72 73 } // namespace 74 75 AudioCodec *newGsmCodec() 76 { 77 return new GsmCodec; 78 } 79
