"a2dp-codecs.h" copied from bluez, then added a2dp_aptxhd_t,
a2dp_ldac_t.
I don't want to debate too much about naming.
On Thursday 13 December 2018 19:43:36 EHfive wrote:
+#define A2DP_CODEC_SBC 0x00
+#define A2DP_CODEC_MPEG12 0x01
+#define A2DP_CODEC_MPEG24 0x02
+#define A2DP_CODEC_ATRAC 0x03
This is incorrect, Atrac codec has A2DP ID 0x04, see:
https://www.bluetooth.com/specifications/assigned-numbers/audio-video
+#define MAX_BITPOOL 64
+#define MIN_BITPOOL 2
These two constants are SBC specific, so make them with SBC_ prefix.
+#define APTX_VENDOR_ID 0x0000004f
This ID is allocated for APT Ltd. company. Not just for aptX codec. So
maybe better name is A2DP_VENDOR_APT_LIC_LTD?
+#define APTX_CODEC_ID 0x0001
+
+#define APTX_CHANNEL_MODE_MONO 0x01
+#define APTX_CHANNEL_MODE_STEREO 0x02
+
+#define APTX_SAMPLING_FREQ_16000 0x08
+#define APTX_SAMPLING_FREQ_32000 0x04
+#define APTX_SAMPLING_FREQ_44100 0x02
+#define APTX_SAMPLING_FREQ_48000 0x01
+
+#define LDAC_VENDOR_ID 0x0000012d
This ID is allocated for Sony Corporation company. Not just for LDAC
codec.
See: https://www.bluetooth.com/specifications/assigned-numbers/company-identifiers
+#elif __BYTE_ORDER == __BIG_ENDIAN
+
+typedef struct {
+ uint8_t frequency:4;
+ uint8_t channel_mode:4;
+ uint8_t block_length:4;
+ uint8_t subbands:2;
+ uint8_t allocation_method:2;
+ uint8_t min_bitpool;
+ uint8_t max_bitpool;
+} __attribute__ ((packed)) a2dp_sbc_t;
+
+typedef struct {
+ uint8_t layer:3;
+ uint8_t crc:1;
+ uint8_t channel_mode:4;
+ uint8_t rfa:1;
+ uint8_t mpf:1;
+ uint8_t frequency:6;
+ uint16_t bitrate;
This value for big endian systems seems to be broken. As you need to
store value in little endian. So maybe define as?
uint8_t bitrate_low;
uint8_t bitrate_high;
Or as
uint8_t bitrate[2];
Or better drop big endian support? Broken big endian support is not
useful at all.
+static size_t
+pa_sbc_decode(const void *read_buf, size_t read_buf_size, void *write_buf, size_t write_buf_size, size_t *_decoded,
+ uint32_t *timestamp, void **codec_data) {
+ const struct rtp_header *header;
+ const struct rtp_payload *payload;
+ const void *p;
+ void *d;
+ size_t to_write, to_decode;
+ size_t total_written = 0;
+ sbc_info_t *sbc_info = *codec_data;
+ pa_assert(sbc_info);
+
+ header = read_buf;
+ payload = (struct rtp_payload *) ((uint8_t *) read_buf + sizeof(*header));
+
+ *timestamp = ntohl(header->timestamp);
+
+ p = (uint8_t *) read_buf + sizeof(*header) + sizeof(*payload);
+ to_decode = read_buf_size - sizeof(*header) - sizeof(*payload);
+
+ d = write_buf;
+ to_write = write_buf_size;
+
+ *_decoded = 0;
+ while (PA_LIKELY(to_decode > 0)) {
+ size_t written;
+ ssize_t decoded;
+
+ decoded = sbc_decode(&sbc_info->sbc,
+ p, to_decode,
+ d, to_write,
+ &written);
+
+ if (PA_UNLIKELY(decoded <= 0)) {
+ pa_log_error("SBC decoding error (%li)", (long) decoded);
+ *_decoded = 0;
+ return 0;
+ }
+
+ total_written += written;
+
+ /* Reset frame length, it can be changed due to bitpool change */
+ sbc_info->frame_length = sbc_get_frame_length(&sbc_info->sbc);
+
+ pa_assert_fp((size_t) decoded <= to_decode);
+ pa_assert_fp((size_t) decoded == sbc_info->frame_length);
+
+ pa_assert_fp((size_t) written == sbc_info->codesize);
+
+ *_decoded += decoded;
+ p = (const uint8_t *) p + decoded;
+ to_decode -= decoded;
+
+ d = (uint8_t *) d + written;
+ to_write -= written;
+ }
+
+ return total_written;
+}
Seems that this decode procedure with while loop is similar/same for all
codecs. Months ago I sent to this mailing list different proposal for
codec API which tries to "fix" also this problem. Look into mailing list
archive for "[PATCH v2 1/2] Modular API for Bluetooth A2DP codec".
+#define A2DP_SOURCE_ENDPOINT "/MediaEndpoint/A2DPSource"
+#define A2DP_SINK_ENDPOINT "/MediaEndpoint/A2DPSink"
+
+#define A2DP_SBC_SRC_ENDPOINT A2DP_SOURCE_ENDPOINT "/SBC"
+#define A2DP_SBC_SNK_ENDPOINT A2DP_SINK_ENDPOINT "/SBC"
+
+#define A2DP_VENDOR_SRC_ENDPOINT A2DP_SOURCE_ENDPOINT "/VENDOR"
+#define A2DP_VENDOR_SNK_ENDPOINT A2DP_SINK_ENDPOINT "/VENDOR"
This would not work correctly. You need for each codec different
endpoint.
Actually, there do have multiple endpoints .
The result is, it support multi-codec, but can't switch to other
codec.
