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
19extern "C" {
20#include "gsm.h"
21}
22
23namespace {
24
25class GsmCodec : public AudioCodec
26{
27public:
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
49private:
50    gsm mEncode;
51    gsm mDecode;
52};
53
54int GsmCodec::encode(void *payload, int16_t *samples)
55{
56    gsm_encode(mEncode, samples, (unsigned char *)payload);
57    return 33;
58}
59
60int 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
75AudioCodec *newGsmCodec()
76{
77    return new GsmCodec;
78}
79