Beginning of mkv muxer, only EBML head is written correctly

Originally committed as revision 10294 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/matroskaenc.c

+/*
+ * Matroska file muxer
+ * Copyright (c) 2007 David Conrad
+ *
+ * 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 "riff.h"
+#include "matroska.h"
+
+typedef struct MatroskaMuxContext {
+    offset_t    segment;
+} MatroskaMuxContext;
+
+static void put_ebml_id(ByteIOContext *pb, unsigned int id)
+{
+    if (id >= 0x3fffff)
+        put_byte(pb, id >> 24);
+    if (id >= 0x7fff)
+        put_byte(pb, id >> 16);
+    if (id >= 0xff)
+        put_byte(pb, id >> 8);
+    put_byte(pb, id);
+}
+
+// XXX: test this thoroughly and get rid of minbytes hack (currently needed to
+// use up all of the space reserved in start_ebml_master)
+static void put_ebml_size(ByteIOContext *pb, uint64_t size, int minbytes)
+{
+    int bytes = minbytes;
+    while (size >> (bytes*8 + 7-bytes) > 0) bytes++;
+
+    // sizes larger than this are currently undefined in EBML
+    // XXX: error condition?
+    if (size > (1ULL<<56)-1) return;
+
+    put_byte(pb, (0x80 >> bytes) | (size >> bytes*8));
+    for (bytes -= 1; bytes >= 0; bytes--)
+        put_byte(pb, size >> bytes*8);
+}
+
+static void put_ebml_uint(ByteIOContext *pb, unsigned int elementid, uint64_t val)
+{
+    int bytes = 1;
+    while (val >> bytes*8) bytes++;
+
+    put_ebml_id(pb, elementid);
+    put_ebml_size(pb, bytes, 0);
+    for (bytes -= 1; bytes >= 0; bytes--)
+        put_byte(pb, val >> bytes*8);
+}
+
+//static void put_ebml_sint(ByteIOContext *pb, unsigned int elementid, int64_t val)
+
+static void put_ebml_binary(ByteIOContext *pb, unsigned int elementid,
+                            uint8_t *buf, int size)
+{
+    put_ebml_id(pb, elementid);
+    put_ebml_size(pb, size, 0);
+    put_buffer(pb, buf, size);
+}
+
+// XXX: should we do any special checking for valid strings for these 2 functions?
+static void put_ebml_string(ByteIOContext *pb, unsigned int elementid, char *str)
+{
+    put_ebml_binary(pb, elementid, str, strlen(str));
+}
+
+static void put_ebml_utf8(ByteIOContext *pb, unsigned int elementid, char *str)
+{
+    put_ebml_binary(pb, elementid, str, strlen(str));
+}
+
+static offset_t start_ebml_master(ByteIOContext *pb, unsigned int elementid)
+{
+    put_ebml_id(pb, elementid);
+    // XXX: this always reserves the maximum needed space to store any size value
+    // we should be smarter (additional parameter for expected size?)
+    put_ebml_size(pb, (1ULL<<56)-1, 0);     // largest unknown size
+    return url_ftell(pb);
+}
+
+static void end_ebml_master(ByteIOContext *pb, offset_t start)
+{
+    offset_t pos = url_ftell(pb);
+
+    url_fseek(pb, start - 8, SEEK_SET);
+    put_ebml_size(pb, pos - start, 7);
+    url_fseek(pb, pos, SEEK_SET);
+}
+
+
+static int mkv_write_header(AVFormatContext *s)
+{
+    MatroskaMuxContext *mkv = s->priv_data;
+    ByteIOContext *pb = &s->pb;
+    offset_t ebml_header, segment_info, tracks;
+    int i;
+
+    ebml_header = start_ebml_master(pb, EBML_ID_HEADER);
+    put_ebml_uint(pb, EBML_ID_EBMLVERSION, 1);
+    put_ebml_uint(pb, EBML_ID_EBMLREADVERSION, 1);
+    put_ebml_uint(pb, EBML_ID_EBMLMAXIDLENGTH, 4);
+    put_ebml_uint(pb, EBML_ID_EBMLMAXSIZELENGTH, 8);
+    put_ebml_string(pb, EBML_ID_DOCTYPE, "matroska");
+    put_ebml_uint(pb, EBML_ID_DOCTYPEVERSION, 1);
+    put_ebml_uint(pb, EBML_ID_DOCTYPEREADVERSION, 1);
+    end_ebml_master(pb, ebml_header);
+
+    mkv->segment = start_ebml_master(pb, MATROSKA_ID_SEGMENT);
+
+    segment_info = start_ebml_master(pb, MATROSKA_ID_INFO);
+    put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000);
+    if (strlen(s->title))
+        put_ebml_utf8(pb, MATROSKA_ID_TITLE, s->title);
+    if (!(s->streams[0]->codec->flags & CODEC_FLAG_BITEXACT)) {
+        put_ebml_utf8(pb, MATROSKA_ID_MUXINGAPP, LIBAVFORMAT_IDENT);
+        // XXX: both are required; something better for writing app?
+        put_ebml_utf8(pb, MATROSKA_ID_WRITINGAPP, LIBAVFORMAT_IDENT);
+    }
+    // XXX: segment UID and duration
+    end_ebml_master(pb, segment_info);
+
+    tracks = start_ebml_master(pb, MATROSKA_ID_TRACKS);
+    for (i = 0; i < s->nb_streams; i++) {
+        AVStream *st = s->streams[i];
+        offset_t track = start_ebml_master(pb, MATROSKA_ID_TRACKENTRY);
+
+        end_ebml_master(pb, track);
+    }
+    end_ebml_master(pb, tracks);
+
+    put_be64(pb, 0xdeadbeef);
+    return 0;
+}
+
+static int mkv_write_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    ByteIOContext *pb = &s->pb;
+    put_buffer(pb, pkt->data, pkt->size);
+    return 0;
+}
+
+static int mkv_write_trailer(AVFormatContext *s)
+{
+    MatroskaMuxContext *mkv = s->priv_data;
+    ByteIOContext *pb = &s->pb;
+    end_ebml_master(pb, mkv->segment);
+    return 0;
+}
+
+AVOutputFormat matroska_muxer = {
+    "matroska",
+    "Matroska File Format",
+    "video/x-matroska",
+    "mkv",
+    sizeof(MatroskaMuxContext),
+    CODEC_ID_MP2,
+    CODEC_ID_MPEG4,
+    mkv_write_header,
+    mkv_write_packet,
+    mkv_write_trailer,
+    .codec_tag = (const AVCodecTag*[]){codec_bmp_tags, codec_wav_tags, 0},
+};