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:
GsmCodec()28 GsmCodec() {
29 mEncode = gsm_create();
30 mDecode = gsm_create();
31 }
32
~GsmCodec()33 ~GsmCodec() {
34 if (mEncode) {
35 gsm_destroy(mEncode);
36 }
37 if (mDecode) {
38 gsm_destroy(mDecode);
39 }
40 }
41
set(int sampleRate,const char *)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
encode(void * payload,int16_t * samples)54 int GsmCodec::encode(void *payload, int16_t *samples)
55 {
56 gsm_encode(mEncode, samples, (unsigned char *)payload);
57 return 33;
58 }
59
decode(int16_t * samples,int count,void * payload,int length)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
newGsmCodec()75 AudioCodec *newGsmCodec()
76 {
77 return new GsmCodec;
78 }
79