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VGM Codec: Improve time and fade behavior. Tweak minor misc. 

Prevents cutoff of tracks, especially short ones:
* Extend looped tracks by fade length to fade at start of loop repeat.
* No fade occurs for non-repeating track only having an intro.
* Uses id3.tail_trim field to store fade duration.

Use libGME built-in elapsed time reporting instead of custom calculation:
* libGME already reports in milliseconds.
* Don't advance time counter when Repeat == One. It just runs the progress
  over the length limit.

Fix a comment about sample rate and set the reported bitrate to be
accurate for 44.1 kHz stereo.

Change-Id: I3ede22bda0f9a941a3fef751f4d678eb0027344c
This commit is contained in:
Michael Sevakis 2013-03-06 19:36:24 -05:00
parent 2f9e3cae2c
commit c73894213d
2 changed files with 40 additions and 20 deletions
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48
lib/rbcodec/codecs/vgm.c
View File

@ -23,6 +23,31 @@ static char *songbuf; /* destination for uncompressed song */
static uint32_t songbuflen=0; /* size of the song buffer */
static uint32_t songlen=0; /* used size of the song buffer */
static void codec_vgz_update_length(void)
{
ci->id3->length = Track_get_length( &vgm_emu );
ci->id3->tail_trim = 4 * 1000;
if (vgm_emu.info.loop_length <= 0)
ci->id3->tail_trim = 0;
ci->id3->length += ci->id3->tail_trim;
}
static void codec_update_fade(void)
{
/* for REPEAT_ONE we disable track limits */
Track_set_fade(&vgm_emu,
ci->loop_track() ? indefinite_count :
ci->id3->length - ci->id3->tail_trim,
ci->id3->tail_trim);
}
static void codec_update_elapsed(void)
{
ci->set_elapsed(ci->loop_track() ? 0 : Track_tell(&vgm_emu));
}
/****************** rockbox interface ******************/
/* this is the codec entry point */
@ -32,7 +57,7 @@ enum codec_status codec_main(enum codec_entry_call_reason reason)
/* we only render 16 bits */
ci->configure(DSP_SET_SAMPLE_DEPTH, 16);
/* 32 Khz, Interleaved stereo */
/* 44 Khz, Interleaved stereo */
ci->configure(DSP_SET_FREQUENCY, 44100);
ci->configure(DSP_SET_STEREO_MODE, STEREO_INTERLEAVED);
@ -51,8 +76,6 @@ enum codec_status codec_run(void)
size_t n;
intptr_t param;
uint32_t elapsed_time = 0;
DEBUGF("VGM: next_track\n");
if (codec_init()) {
return CODEC_ERROR;
@ -95,7 +118,7 @@ enum codec_status codec_run(void)
/* Since metadata parser doesn't support VGZ
will set song length here */
ci->id3->length = Track_get_length( &vgm_emu );
codec_vgz_update_length();
}
else if ((err = Vgm_load_mem(&vgm_emu, buf, n, false))) {
DEBUGF("VGM: Vgm_load failed_mem (%s)\n", err);
@ -104,12 +127,8 @@ enum codec_status codec_run(void)
Vgm_start_track(&vgm_emu);
/* for REPEAT_ONE we disable track limits */
if (!ci->loop_track()) {
Track_set_fade(&vgm_emu, ci->id3->length - 4000, 4000);
}
ci->set_elapsed(0);
codec_update_fade();
/* The main decoder loop */
while (1) {
@ -119,23 +138,20 @@ enum codec_status codec_run(void)
break;
if (action == CODEC_ACTION_SEEK_TIME) {
ci->set_elapsed(param);
elapsed_time = param;
Track_seek(&vgm_emu, param);
codec_update_elapsed();
ci->seek_complete();
/* Set fade again in case we seek to start of song */
Track_set_fade(&vgm_emu, ci->id3->length - 4000, 4000);
codec_update_fade();
}
/* Generate audio buffer */
err = Vgm_play(&vgm_emu, CHUNK_SIZE, samples);
if (err || Track_ended(&vgm_emu)) break;
ci->pcmbuf_insert(samples, NULL, CHUNK_SIZE >> 1);
elapsed_time += (CHUNK_SIZE / 2) * 10 / 441;
ci->set_elapsed(elapsed_time);
ci->pcmbuf_insert(samples, NULL, CHUNK_SIZE / 2);
codec_update_elapsed();
}
return CODEC_OK;

12
lib/rbcodec/metadata/vgm.c
View File

@ -113,6 +113,8 @@ static long check_gd3_header( byte* h, long remain )
static void get_vgm_length( struct header_t* h, struct mp3entry* id3 )
{
long length = get_long_le( h->track_duration ) * 10 / 441;
id3->tail_trim = 4 * 1000; /* assume fade */
if ( length > 0 )
{
long loop_length = 0, intro_length = 0;
@ -126,13 +128,15 @@ static void get_vgm_length( struct header_t* h, struct mp3entry* id3 )
{
intro_length = length; /* make it clear that track is no longer than length */
loop_length = 0;
id3->tail_trim = 0;
}
id3->length = intro_length + 2 * loop_length; /* intro + 2 loops */
return;
/* intro + 2 loops + fade */
id3->length = intro_length + 2 * loop_length + id3->tail_trim;
return;
}
id3->length = 150 * 1000; /* 2.5 minutes */
id3->length = 150 * 1000 + id3->tail_trim; /* 2.5 minutes + fade */
}
bool get_vgm_metadata(int fd, struct mp3entry* id3)
@ -151,7 +155,7 @@ bool get_vgm_metadata(int fd, struct mp3entry* id3)
id3->vbr = false;
id3->filesize = filesize(fd);
id3->bitrate = 706;
id3->bitrate = 1411;
id3->frequency = 44100;
/* If file is gzipped, will get metadata later */