diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/pcm_convert.c | 35 | ||||
| -rw-r--r-- | src/pcm_dsd_usb.c | 74 | ||||
| -rw-r--r-- | src/pcm_dsd_usb.h | 41 |
3 files changed, 150 insertions, 0 deletions
diff --git a/src/pcm_convert.c b/src/pcm_convert.c index 03172b613..f19a95223 100644 --- a/src/pcm_convert.c +++ b/src/pcm_convert.c @@ -22,6 +22,7 @@ #include "pcm_channels.h" #include "pcm_format.h" #include "pcm_pack.h" +#include "pcm_dsd_usb.h" #include "audio_format.h" #include "glib_compat.h" @@ -325,6 +326,40 @@ pcm_convert(struct pcm_convert_state *state, size_t *dest_size_r, GError **error_r) { + struct audio_format usb_format; + + if (src_format->format == SAMPLE_FORMAT_DSD && + dest_format->format == SAMPLE_FORMAT_DSD_OVER_USB) { + size_t u_size; + const uint32_t *u = pcm_dsd_to_usb(&state->dsd.buffer, + src_format->channels, + src, src_size, + &u_size); + if (u == NULL) { + g_set_error_literal(error_r, pcm_convert_quark(), 0, + "DSD to USB conversion failed"); + return NULL; + } + + usb_format = *src_format; + usb_format.format = SAMPLE_FORMAT_DSD_OVER_USB; + + /* each DSD-over-USB sample contains 2 DSD bytes (16 + DSD bits), which means the sample rate must be + halved; this is not the real 1 bit sample rate, but + MPD's point of view */ + usb_format.sample_rate = usb_format.sample_rate / 2; + + if (audio_format_equals(&usb_format, dest_format)) { + *dest_size_r = u_size; + return u; + } + + src_format = &usb_format; + src = u; + src_size = u_size; + } + struct audio_format float_format; if (src_format->format == SAMPLE_FORMAT_DSD) { size_t f_size; diff --git a/src/pcm_dsd_usb.c b/src/pcm_dsd_usb.c new file mode 100644 index 000000000..976420c00 --- /dev/null +++ b/src/pcm_dsd_usb.c @@ -0,0 +1,74 @@ +/* + * Copyright (C) 2003-2012 The Music Player Daemon Project + * http://www.musicpd.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#include "config.h" +#include "pcm_dsd_usb.h" +#include "pcm_buffer.h" +#include "audio_format.h" + +G_GNUC_CONST +static inline uint32_t +pcm_two_dsd_to_usb(uint8_t a, uint8_t b) +{ + return 0xffaa0000 | (a << 8) | b; +} + +const uint32_t * +pcm_dsd_to_usb(struct pcm_buffer *buffer, unsigned channels, + const uint8_t *src, size_t src_size, + size_t *dest_size_r) +{ + assert(buffer != NULL); + assert(audio_valid_channel_count(channels)); + assert(src != NULL); + assert(src_size > 0); + assert(src_size % channels == 0); + + const unsigned num_src_samples = src_size; + const unsigned num_src_frames = num_src_samples / channels; + + /* this rounds down and discards the last odd frame; not + elegant, but good enough for now */ + const unsigned num_frames = num_src_frames / 2; + const unsigned num_samples = num_frames * channels; + + const size_t dest_size = num_samples * 4; + *dest_size_r = dest_size; + uint32_t *const dest0 = pcm_buffer_get(buffer, dest_size), + *dest = dest0; + + for (unsigned i = num_frames; i > 0; --i) { + for (unsigned c = channels; c > 0; --c) { + /* each 24 bit sample has 16 DSD sample bits + plus the magic 0xaa marker */ + + *dest++ = pcm_two_dsd_to_usb(src[0], src[channels]); + + /* seek the source pointer to the next + channel */ + ++src; + } + + /* skip the second byte of each channel, because we + have already copied it */ + src += channels; + } + + return dest0; +} diff --git a/src/pcm_dsd_usb.h b/src/pcm_dsd_usb.h new file mode 100644 index 000000000..3e7ad8fa1 --- /dev/null +++ b/src/pcm_dsd_usb.h @@ -0,0 +1,41 @@ +/* + * Copyright (C) 2003-2012 The Music Player Daemon Project + * http://www.musicpd.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#ifndef MPD_PCM_DSD_USB_H +#define MPD_PCM_DSD_USB_H + +#include "check.h" + +#include <stdbool.h> +#include <stdint.h> +#include <stddef.h> + +struct pcm_buffer; + +/** + * Pack DSD 1 bit samples into (padded) 24 bit PCM samples for + * playback over USB, according to the dCS suggested standard: + * http://www.dcsltd.co.uk/page/assets/DSDoverUSB.pdf + */ +const uint32_t * +pcm_dsd_to_usb(struct pcm_buffer *buffer, unsigned channels, + const uint8_t *src, size_t src_size, + size_t *dest_size_r); + +#endif |