resampler.h revision b3184d71bc6cee9fcbb36343e379143329be00ce 
1/*
2** Copyright 2008, 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#ifndef ANDROID_RESAMPLER_H
18#define ANDROID_RESAMPLER_H
19
20#include <stdint.h>
21#include <sys/time.h>
22
23__BEGIN_DECLS
24
25
26#define RESAMPLER_QUALITY_MAX 10
27#define RESAMPLER_QUALITY_MIN 0
28#define RESAMPLER_QUALITY_DEFAULT 4
29#define RESAMPLER_QUALITY_VOIP 3
30#define RESAMPLER_QUALITY_DESKTOP 5
31
32struct resampler_buffer {
33    union {
34        void*       raw;
35        short*      i16;
36        int8_t*     i8;
37    };
38    size_t frame_count;
39};
40
41/* call back interface used by the resampler to get new data */
42struct resampler_buffer_provider
43{
44    /**
45     *  get a new buffer of data:
46     *   as input: buffer->frame_count is the number of frames requested
47     *   as output: buffer->frame_count is the number of frames returned
48     *              buffer->raw points to data returned
49     */
50    int (*get_next_buffer)(struct resampler_buffer_provider *provider,
51            struct resampler_buffer *buffer);
52    /**
53     *  release a consumed buffer of data:
54     *   as input: buffer->frame_count is the number of frames released
55     *             buffer->raw points to data released
56     */
57    void (*release_buffer)(struct resampler_buffer_provider *provider,
58            struct resampler_buffer *buffer);
59};
60
61/* resampler interface */
62struct resampler_itfe {
63    /**
64     * reset resampler state
65     */
66    void (*reset)(struct resampler_itfe *resampler);
67    /**
68     * resample input from buffer provider and output at most *outFrameCount to out buffer.
69     * *outFrameCount is updated with the actual number of frames produced.
70     */
71    int (*resample_from_provider)(struct resampler_itfe *resampler,
72                    int16_t *out,
73                    size_t *outFrameCount);
74    /**
75     * resample at most *inFrameCount frames from in buffer and output at most
76     * *outFrameCount to out buffer. *inFrameCount and *outFrameCount are updated respectively
77     * with the number of frames remaining in input and written to output.
78     */
79    int (*resample_from_input)(struct resampler_itfe *resampler,
80                    int16_t *in,
81                    size_t *inFrameCount,
82                    int16_t *out,
83                    size_t *outFrameCount);
84    /**
85     * return the latency introduced by the resampler in ns.
86     */
87    int32_t (*delay_ns)(struct resampler_itfe *resampler);
88};
89
90/**
91 * create a resampler according to input parameters passed.
92 * If resampler_buffer_provider is not NULL only resample_from_provider() can be called.
93 * If resampler_buffer_provider is NULL only resample_from_input() can be called.
94 */
95int create_resampler(uint32_t inSampleRate,
96          uint32_t outSampleRate,
97          uint32_t channelCount,
98          uint32_t quality,
99          struct resampler_buffer_provider *provider,
100          struct resampler_itfe **);
101
102/**
103 * release resampler resources.
104 */
105void release_resampler(struct resampler_itfe *);
106
107__END_DECLS
108
109#endif // ANDROID_RESAMPLER_H
110