diff options
| -rw-r--r-- | src/audio_format.h | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/src/audio_format.h b/src/audio_format.h index 6373d1e80..cf067b705 100644 --- a/src/audio_format.h +++ b/src/audio_format.h @@ -23,13 +23,42 @@ #include <stdint.h> #include <stdbool.h> +/** + * This structure describes the format of a raw PCM stream. + */ struct audio_format { + /** + * The sample rate in Hz. A better name for this attribute is + * "frame rate", because technically, you have two samples per + * frame in stereo sound. + */ uint32_t sample_rate; + + /** + * The number of significant bits per sample. Samples are + * currently always signed. Supported values are 8, 16, 24, + * 32. 24 bit samples are packed in 32 bit integers. + */ uint8_t bits; + + /** + * The number of channels. Only mono (1) and stereo (2) are + * fully supported currently. + */ uint8_t channels; + + /** + * If zero, then samples are stored in host byte order. If + * nonzero, then samples are stored in the reverse host byte + * order. + */ uint8_t reverse_endian; }; +/** + * Clears the #audio_format object, i.e. sets all attributes to an + * undefined (invalid) value. + */ static inline void audio_format_clear(struct audio_format *af) { af->sample_rate = 0; @@ -38,6 +67,10 @@ static inline void audio_format_clear(struct audio_format *af) af->reverse_endian = 0; } +/** + * Initializes an #audio_format object, i.e. sets all + * attributes to valid values. + */ static inline void audio_format_init(struct audio_format *af, uint32_t sample_rate, uint8_t bits, uint8_t channels) @@ -48,6 +81,10 @@ static inline void audio_format_init(struct audio_format *af, af->reverse_endian = 0; } +/** + * Checks whether the specified #audio_format object has a defined + * value. + */ static inline bool audio_format_defined(const struct audio_format *af) { return af->sample_rate != 0; @@ -117,17 +154,28 @@ static inline unsigned audio_format_sample_size(const struct audio_format *af) return 4; } +/** + * Returns the size of each full frame in bytes. + */ static inline unsigned audio_format_frame_size(const struct audio_format *af) { return audio_format_sample_size(af) * af->channels; } +/** + * Returns the floating point factor which converts a time span to a + * storage size in bytes. + */ static inline double audio_format_time_to_size(const struct audio_format *af) { return af->sample_rate * audio_format_frame_size(af); } +/** + * Returns the floating point factor which converts a storage size in + * bytes to a time span. + */ static inline double audioFormatSizeToTime(const struct audio_format *af) { return 1.0 / audio_format_time_to_size(af); |