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 #include "gsm.h"
20
21 namespace {
22
23 class GsmCodec : public AudioCodec
24 {
25 public:
GsmCodec()26 GsmCodec() {
27 mEncode = gsm_create();
28 mDecode = gsm_create();
29 }
30
~GsmCodec()31 ~GsmCodec() {
32 if (mEncode) {
33 gsm_destroy(mEncode);
34 }
35 if (mDecode) {
36 gsm_destroy(mDecode);
37 }
38 }
39
set(int sampleRate,const char *)40 int set(int sampleRate, const char */* fmtp */) {
41 return (sampleRate == 8000 && mEncode && mDecode) ? 160 : -1;
42 }
43
44 int encode(void *payload, int16_t *samples);
45 int decode(int16_t *samples, int count, void *payload, int length);
46
47 private:
48 gsm mEncode;
49 gsm mDecode;
50 };
51
encode(void * payload,int16_t * samples)52 int GsmCodec::encode(void *payload, int16_t *samples)
53 {
54 gsm_encode(mEncode, samples, (unsigned char *)payload);
55 return 33;
56 }
57
decode(int16_t * samples,int count,void * payload,int length)58 int GsmCodec::decode(int16_t *samples, int count, void *payload, int length)
59 {
60 unsigned char *bytes = (unsigned char *)payload;
61 int n = 0;
62 while (n + 160 <= count && length >= 33 &&
63 gsm_decode(mDecode, bytes, &samples[n]) == 0) {
64 n += 160;
65 length -= 33;
66 bytes += 33;
67 }
68 return n;
69 }
70
71 } // namespace
72
newGsmCodec()73 AudioCodec *newGsmCodec()
74 {
75 return new GsmCodec;
76 }
77