From 26fae61845e0b058e734dacbc6c5a6dee0252440 Mon Sep 17 00:00:00 2001 From: Thibaut Mattern Date: Fri, 4 Jan 2008 23:36:14 +0100 Subject: Initial parsing of Xing header LAME extension. --- src/demuxers/demux_mpgaudio.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) (limited to 'src') diff --git a/src/demuxers/demux_mpgaudio.c b/src/demuxers/demux_mpgaudio.c index 8e716f095..61c0d4cb5 100644 --- a/src/demuxers/demux_mpgaudio.c +++ b/src/demuxers/demux_mpgaudio.c @@ -65,11 +65,13 @@ /* Xing header stuff */ #define XING_TAG FOURCC_TAG('X', 'i', 'n', 'g') #define INFO_TAG FOURCC_TAG('I', 'n', 'f', 'o') +#define LAME_TAG FOURCC_TAG('L', 'A', 'M', 'E') #define XING_FRAMES_FLAG 0x0001 #define XING_BYTES_FLAG 0x0002 #define XING_TOC_FLAG 0x0004 #define XING_VBR_SCALE_FLAG 0x0008 #define XING_TOC_LENGTH 100 +#define LAME_HEADER_LENGTH 0xC0 /* Xing header stuff */ #define VBRI_TAG FOURCC_TAG('V', 'B', 'R', 'I') @@ -96,6 +98,10 @@ typedef struct { uint32_t stream_size; uint8_t toc[XING_TOC_LENGTH]; uint32_t vbr_scale; + + /* Lame extension */ + uint16_t start_delay; + uint16_t end_delay; } xing_header_t; /* Vbri Vbr Header struct */ @@ -380,9 +386,21 @@ static xing_header_t* parse_xing_header(mpg_audio_frame_t *frame, xing->vbr_scale = -1; if (xing->flags & XING_VBR_SCALE_FLAG) { if (ptr >= (buf + bufsize - 4)) goto exit_error; - xing->vbr_scale = _X_BE_32(ptr); + xing->vbr_scale = _X_BE_32(ptr); ptr += 4; lprintf("vbr_scale: %d\n", xing->vbr_scale); } + + /* LAME extension */ + /* see http://gabriel.mp3-tech.org/mp3infotag.html */ + ptr -= 0x9C; /* move offset to match LAME header specs */ + if (ptr + LAME_HEADER_LENGTH >= (buf + bufsize - 4)) goto exit_error; + if (_X_BE_32(&ptr[0x9C]) == LAME_TAG) { + lprintf("Lame header found\n"); + xing->start_delay = (ptr[0xb1] << 4) | (ptr[0xb2] >> 4); + xing->end_delay = ((ptr[0xb2] & 0x0f) << 4) | ptr[0xb3]; + lprintf("start delay : %d samples\n", xing->start_delay); + lprintf("end delay : %d samples\n", xing->end_delay); + } } else { lprintf("Xing header not found\n"); } -- cgit v1.2.3