From fd6fd470ce47d1b68067a16120ffc87fa25ffa01 Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Thu, 5 Mar 2009 01:15:38 +0000 Subject: [PATCH] flacdec: Simplify frame sync by not using the bitstream reader. Originally committed as revision 17818 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/flacdec.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/libavcodec/flacdec.c b/libavcodec/flacdec.c index 29e3739688..893eab5705 100644 --- a/libavcodec/flacdec.c +++ b/libavcodec/flacdec.c @@ -610,7 +610,7 @@ static int flac_decode_frame(AVCodecContext *avctx, const uint8_t *buf, int buf_size) { FLACContext *s = avctx->priv_data; - int tmp = 0, i, j = 0, input_buf_size = 0, bytes_read = 0; + int i, j = 0, input_buf_size = 0, bytes_read = 0; int16_t *samples_16 = data; int32_t *samples_32 = data; int alloc_data_size= *data_size; @@ -664,15 +664,18 @@ static int flac_decode_frame(AVCodecContext *avctx, goto end; } - init_get_bits(&s->gb, buf, buf_size*8); - - tmp = show_bits(&s->gb, 16); - if ((tmp & 0xFFFE) != 0xFFF8) { + /* check for frame sync code and resync stream if necessary */ + if ((AV_RB16(buf) & 0xFFFE) != 0xFFF8) { + const uint8_t *buf_end = buf + buf_size; av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n"); - while (get_bits_count(&s->gb)/8+2 < buf_size && (show_bits(&s->gb, 16) & 0xFFFE) != 0xFFF8) - skip_bits(&s->gb, 8); - goto hdr_end; // we may not have enough bits left to decode a frame, so try next time + while (buf+2 < buf_end && (AV_RB16(buf) & 0xFFFE) != 0xFFF8) + buf++; + bytes_read = buf_size - (buf_end - buf); + goto end; // we may not have enough bits left to decode a frame, so try next time } + + /* decode frame */ + init_get_bits(&s->gb, buf, buf_size*8); skip_bits(&s->gb, 16); if (decode_frame(s, alloc_data_size) < 0) { av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n"); @@ -717,7 +720,6 @@ static int flac_decode_frame(AVCodecContext *avctx, *data_size = s->blocksize * s->channels * (s->is32 ? 4 : 2); -hdr_end: bytes_read = (get_bits_count(&s->gb)+7)/8; end: if (bytes_read > buf_size) {