ffmpeg source update for sep 09

source/patched-ffmpeg-mt/libavformat/pcm.c

+/*
+ * PCM common functions
+ * Copyright (c) 2003 Fabrice Bellard
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avformat.h"
+#include "pcm.h"
+
+int pcm_read_seek(AVFormatContext *s,
+                  int stream_index, int64_t timestamp, int flags)
+{
+    AVStream *st;
+    int block_align, byte_rate;
+    int64_t pos, ret;
+
+    st = s->streams[0];
+
+    block_align = st->codec->block_align ? st->codec->block_align :
+        (av_get_bits_per_sample(st->codec->codec_id) * st->codec->channels) >> 3;
+    byte_rate = st->codec->bit_rate ? st->codec->bit_rate >> 3 :
+        block_align * st->codec->sample_rate;
+
+    if (block_align <= 0 || byte_rate <= 0)
+        return -1;
+    if (timestamp < 0) timestamp = 0;
+
+    /* compute the position by aligning it to block_align */
+    pos = av_rescale_rnd(timestamp * byte_rate,
+                         st->time_base.num,
+                         st->time_base.den * (int64_t)block_align,
+                         (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
+    pos *= block_align;
+
+    /* recompute exact position */
+    st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num);
+    if ((ret = url_fseek(s->pb, pos + s->data_offset, SEEK_SET)) < 0)
+        return ret;
+    return 0;
+}