add xWMA demuxer

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

1 files changed, 254 insertions, 0 deletions

diff --git a/libavformat/xwma.c b/libavformat/xwma.c
new file mode 100644
index 0000000000..4238054476
--- /dev/null
+++ b/libavformat/xwma.c
@@ -0,0 +1,254 @@
+/*
+ * xWMA demuxer
+ * Copyright (c) 2011 Max Horn
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avformat.h"
+#include "riff.h"
+
+/*
+ * Demuxer for xWMA, a Microsoft audio container used by XAudio 2.
+ */
+
+typedef struct {
+    int64_t data_end;
+} XWMAContext;
+
+static int xwma_probe(AVProbeData *p)
+{
+    if (!memcmp(p->buf, "RIFF", 4) && !memcmp(p->buf + 8, "XWMA", 4))
+        return AVPROBE_SCORE_MAX;
+    return 0;
+}
+
+static int xwma_read_header(AVFormatContext *s, AVFormatParameters *ap)
+{
+    int64_t size, av_uninit(data_size);
+    uint32_t dpds_table_size = 0;
+    uint32_t *dpds_table = 0;
+    unsigned int tag;
+    AVIOContext *pb = s->pb;
+    AVStream *st;
+    XWMAContext *xwma = s->priv_data;
+    int i;
+
+    /* The following code is mostly copied from wav.c, with some
+     * minor alterations.
+     */
+
+    /* check RIFF header */
+    tag = avio_rl32(pb);
+    if (tag != MKTAG('R', 'I', 'F', 'F'))
+        return -1;
+    avio_rl32(pb); /* file size */
+    tag = avio_rl32(pb);
+    if (tag != MKTAG('X', 'W', 'M', 'A'))
+        return -1;
+
+    /* parse fmt header */
+    tag = avio_rl32(pb);
+    if (tag != MKTAG('f', 'm', 't', ' '))
+        return -1;
+    size = avio_rl32(pb);
+    st = av_new_stream(s, 0);
+    if (!st)
+        return AVERROR(ENOMEM);
+
+    ff_get_wav_header(pb, st->codec, size);
+    st->need_parsing = AVSTREAM_PARSE_NONE;
+
+    /* All xWMA files I have seen contained WMAv2 data. If there are files
+     * using WMA Pro or some other codec, then we need to figure out the right
+     * extradata for that. Thus, ask the user for feedback, but try to go on
+     * anyway.
+     */
+    if (st->codec->codec_id != CODEC_ID_WMAV2) {
+        av_log(s, AV_LOG_WARNING, "unexpected codec (tag 0x04%x; id %d)\n",
+                              st->codec->codec_tag, st->codec->codec_id);
+        av_log_ask_for_sample(s, NULL);
+    } else {
+        /* In all xWMA files I have seen, there is no extradata. But the WMA
+         * codecs require extradata, so we provide our own fake extradata.
+         *
+         * First, check that there really was no extradata in the header. If
+         * there was, then try to use, after asking the the user to provide a
+         * sample of this unusual file.
+         */
+        if (st->codec->extradata_size != 0) {
+            /* Surprise, surprise: We *did* get some extradata. No idea
+             * if it will work, but just go on and try it, after asking
+             * the user for a sample.
+             */
+            av_log(s, AV_LOG_WARNING, "unexpected extradata (%d bytes)\n",
+                                  st->codec->extradata_size);
+            av_log_ask_for_sample(s, NULL);
+        } else {
+            st->codec->extradata_size = 6;
+            st->codec->extradata      = av_mallocz(6 + FF_INPUT_BUFFER_PADDING_SIZE);
+            if (!st->codec->extradata)
+                return AVERROR(ENOMEM);
+
+            /* setup extradata with our experimentally obtained value */
+            st->codec->extradata[4] = 31;
+        }
+    }
+
+    /* set the sample rate */
+    av_set_pts_info(st, 64, 1, st->codec->sample_rate);
+
+    /* parse the remaining RIFF chunks */
+    for (;;) {
+        if (pb->eof_reached)
+            return -1;
+        /* read next chunk tag */
+        tag = avio_rl32(pb);
+        size = avio_rl32(pb);
+        if (tag == MKTAG('d', 'a', 't', 'a')) {
+            /* We assume that the data chunk comes last. */
+            break;
+        } else if (tag == MKTAG('d','p','d','s')) {
+            /* Quoting the MSDN xWMA docs on the dpds chunk: "Contains the
+             * decoded packet cumulative data size array, each element is the
+             * number of bytes accumulated after the corresponding xWMA packet
+             * is decoded in order"
+             *
+             * Each packet has size equal to st->codec->block_align, which in
+             * all cases I saw so far was always 2230. Thus, we can use the
+             * dpds data to compute a seeking index.
+             */
+
+            /* Error out if there is more than one dpds chunk. */
+            if (dpds_table) {
+                av_log(s, AV_LOG_ERROR, "two dpds chunks present\n");
+                return -1;
+            }
+
+            /* Compute the number of entries in the dpds chunk. */
+            if (size & 3) {  /* Size should be divisible by four */
+                av_log(s, AV_LOG_WARNING, "dpds chunk size "PRId64" not divisible by 4\n", size);
+            }
+            dpds_table_size = size / 4;
+            if (dpds_table_size == 0 || dpds_table_size >= INT_MAX / 4) {
+                av_log(s, AV_LOG_ERROR, "dpds chunk size "PRId64" invalid\n", size);
+                return -1;
+            }
+
+            /* Allocate some temporary storage to keep the dpds data around.
+             * for processing later on.
+             */
+            dpds_table = av_malloc(dpds_table_size * sizeof(uint32_t));
+            if (!dpds_table) {
+                return AVERROR(ENOMEM);
+            }
+
+            for (i = 0; i < dpds_table_size; ++i) {
+                dpds_table[i] = avio_rl32(pb);
+                size -= 4;
+            }
+        }
+        avio_skip(pb, size);
+    }
+
+    /* Determine overall data length */
+    if (size < 0)
+        return -1;
+    if (!size) {
+        xwma->data_end = INT64_MAX;
+    } else
+        xwma->data_end = avio_tell(pb) + size;
+
+
+    if (dpds_table && dpds_table_size) {
+        int64_t cur_pos;
+        const uint32_t bytes_per_sample
+                = (st->codec->channels * st->codec->bits_per_coded_sample) >> 3;
+
+        /* Estimate the duration from the total number of output bytes. */
+        const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1];
+        st->duration = total_decoded_bytes / bytes_per_sample;
+
+        /* Use the dpds data to build a seek table.  We can only do this after
+         * we know the offset to the data chunk, as we need that to determine
+         * the actual offset to each input block.
+         * Note: If we allowed ourselves to assume that the data chunk always
+         * follows immediately after the dpds block, we could of course guess
+         * the data block's start offset already while reading the dpds chunk.
+         * I decided against that, just in case other chunks ever are
+         * discovered.
+         */
+        cur_pos = avio_tell(pb);
+        for (i = 0; i < dpds_table_size; ++i) {
+            /* From the number of output bytes that would accumulate in the
+             * output buffer after decoding the first (i+1) packets, we compute
+             * an offset / timestamp pair.
+             */
+            av_add_index_entry(st,
+                               cur_pos + (i+1) * st->codec->block_align, /* pos */
+                               dpds_table[i] / bytes_per_sample,         /* timestamp */
+                               st->codec->block_align,                   /* size */
+                               0,                                        /* duration */
+                               AVINDEX_KEYFRAME);
+        }
+    } else if (st->codec->bit_rate) {
+        /* No dpds chunk was present (or only an empty one), so estimate
+         * the total duration using the average bits per sample and the
+         * total data length.
+         */
+        st->duration = (size<<3) * st->codec->sample_rate / st->codec->bit_rate;
+    }
+
+    av_free(dpds_table);
+
+    return 0;
+}
+
+static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    int ret, size;
+    int64_t left;
+    AVStream *st;
+    XWMAContext *xwma = s->priv_data;
+
+    st = s->streams[0];
+
+    left = xwma->data_end - avio_tell(s->pb);
+    if (left <= 0) {
+        return AVERROR_EOF;
+    }
+
+    /* read a single block; the default block size is 2230. */
+    size = (st->codec->block_align > 1) ? st->codec->block_align : 2230;
+    size = FFMIN(size, left);
+
+    ret  = av_get_packet(s->pb, pkt, size);
+    if (ret < 0)
+        return ret;
+
+    pkt->stream_index = 0;
+    return ret;
+}
+
+AVInputFormat ff_xwma_demuxer = {
+    "xwma",
+    NULL_IF_CONFIG_SMALL("Microsoft xWMA"),
+    sizeof(XWMAContext),
+    xwma_probe,
+    xwma_read_header,
+    xwma_read_packet,
+};