private static void ParseChunkIndex(AtomicBinaryReader reader, long p, ref AviStreamIndex index)
{
// read ix.. chunk id and size. do sanity check
uint ixChunkFCC = reader.ReadUInt32(ref p);
uint ixChunkFCCb = (ixChunkFCC & 0x0000FFFF) | 0x20200000;
if (ixChunkFCCb != RiffParser.ToFourCC("ix ") && ixChunkFCC != RiffParser.ToFourCC("indx"))
{
throw new MpException("Unexpected chunk id for index " + RiffParser.FromFourCC(ixChunkFCC) +
" for stream " + RiffParser.FromFourCC(index.streamId));
}
uint ixChunkSize = reader.ReadUInt32(ref p);
// read index data header and do sanity check
ushort wLongsPerEntry = reader.ReadUInt16(ref p);
byte bSubIndexType = reader.ReadByte(ref p);
byte bIndexType = reader.ReadByte(ref p);
uint nEntriesInUse = reader.ReadUInt32(ref p);
uint streamId = reader.ReadUInt32(ref p);
#if MP_DEBUG
//Debug.Log("Parsing index for " + RiffParser.FromFourCC(index.streamId));
#endif
if (bIndexType != (int)AviStreamIndex.Type.CHUNKS || bSubIndexType != 0 || streamId != index.streamId ||
wLongsPerEntry != 2 || ixChunkSize < 4 * wLongsPerEntry * nEntriesInUse + 24)
{
throw new MpException("Broken or unsupported index for stream " + RiffParser.FromFourCC(streamId) +
". " + streamId + "!=" + index.streamId + ", wLongsPerEntry=" + wLongsPerEntry +
", bIndexType=" + bIndexType + ", bSubIndexType=" + bSubIndexType);
}
long qwBaseOffset = reader.ReadInt64(ref p);
p += 4; // not caring about reserved bytes
// reading it all at once is about 10x faster than reading individual uints.
// the index chunk is not that big, so it's ok for GC too.
var uintBuf = new uint[nEntriesInUse * 2];
reader.Read(ref p, uintBuf, 0, (int)nEntriesInUse * 2);
for (int i = 0; i < nEntriesInUse; i++)
{
var entry = new AviStreamIndex.Entry();
entry.chunkOffset = qwBaseOffset + uintBuf [2 * i];
uint len = uintBuf [2 * i + 1];
entry.chunkLength = (int)(len & 0x7FFFFFFF);
if ((len & 0x80000000) == 0)
{
entry.isKeyframe = true;
}
index.entries.Add(entry);
}
}
private static void WriteChunkIndex(RiffWriter rw, AviStreamIndex index, int superIndexChunkOffset, ref int superIndexEntryCount, long indexBaseOffset, int maxSuperindexEntries)
{
var bw = rw.binaryWriter;
// the offset where this index will be written
long streamIndexOffset = bw.Seek(0, SeekOrigin.Current);
// update stream superindex
superIndexEntryCount++;
if (superIndexEntryCount > maxSuperindexEntries)
{
throw new MpException("Not enough space was reserved for superindex. Please increase maxSuperindexEntries");
}
bw.Seek(superIndexChunkOffset + 1 * 4, SeekOrigin.Begin);
bw.Write(superIndexEntryCount); // overwrite nEntriesInUse
bw.Seek(superIndexChunkOffset + 6 * 4 + (superIndexEntryCount - 1) * 16, SeekOrigin.Begin);
bw.Write(streamIndexOffset);
bw.Write(32 + 8 * index.entries.Count); // dwSize
bw.Write(index.entries.Count); // dwDuration in stream ticks. @todo this is OK only for video, for audio stream this should be ???
// write stream chunk index
// @xxx MSDN suggests not seeking BaseStream when using BinaryWriter, but there are no Seek(long)
// in BinaryWriter. According to this forum post, BinaryWriter.Seek is just a wrapper
// to BinaryWriter.BaseStream.Seek, so all should be ok.
// http://www.pcreview.co.uk/forums/binarywriter-seek-vs-binarywriter-basestream-seek-t1223754.html
bw.BaseStream.Seek(streamIndexOffset, SeekOrigin.Begin);
rw.BeginChunk((RiffParser.ToFourCC("ix__") & 0x0000FFFF) | ((index.streamId << 16) & 0xFFFF0000));
bw.Write((short)2); // wLongsPerEntry is always 2 here
bw.Write((byte)0); // bIndexSubType is always 0 here
bw.Write((byte)AviStreamIndex.Type.CHUNKS); // bIndexType = AVI_INDEX_OF_CHUNKS
bw.Write(index.entries.Count); // nEntriesInUse.
bw.Write(index.streamId); // dwChunkId ("##dc" and similar)
bw.Write(indexBaseOffset); // qwBaseOffset
bw.Write((int)0); // dwReserved3
foreach (var entry in index.entries)
{
long offset = entry.chunkOffset - indexBaseOffset;
if (offset > int.MaxValue)
{
throw new MpException("Internal error. Can't write index, because chunk offset won't fit into 31 bits: " + offset);
}
bw.Write((uint)offset); // bit31==0 indicating that this is a keyframe
bw.Write(entry.chunkLength);
}
rw.EndChunk();
index.globalOffset += index.entries.Count;
index.entries.Clear();
}