Optional LZ4 compression for demo files

Per-frame entity and playerState blocks are compressed with LZ4
when svdemo_compress is set (default: 1). The block format writes
[original_size][compressed_size][data] — compressed_size=0 means
uncompressed. Playback auto-detects based on header flags.

Demo format bumped to version 2 with SVDEMO_FLAG_COMPRESSED flag.
Version 1 (uncompressed) demos are no longer compatible.

Uses the lz4.c/lz4.h library already in the server code directory.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
serge_shubin 2026-03-23 05:22:41 +08:00
parent d2b82580ef
commit 330cc30ae7
3 changed files with 81 additions and 20 deletions

View file

@ -997,6 +997,8 @@
</ClCompile>
<ClCompile Include="server\sv_netdemo.c">
</ClCompile>
<ClCompile Include="server\lz4.c">
</ClCompile>
<ClCompile Include="server\sv_world.c">
<Optimization Condition="'$(Configuration)|$(Platform)'=='Debug TA DEMO|Win32'">Disabled</Optimization>
<BrowseInformation Condition="'$(Configuration)|$(Platform)'=='Debug TA DEMO|Win32'">true</BrowseInformation>

View file

@ -621,8 +621,9 @@ void SV_Init (void) {
sv_lanForceRate = Cvar_Get ("sv_lanForceRate", "1", CVAR_ARCHIVE );
sv_strictAuth = Cvar_Get ("sv_strictAuth", "1", CVAR_ARCHIVE );
// server-side demo auto-recording
// server-side demo settings
Cvar_Get ("svdemo_autorecord", "0", CVAR_ARCHIVE);
Cvar_Get ("svdemo_compress", "1", CVAR_ARCHIVE);
// initialize bot cvars so they are listed and can be set before loading the botlib
SV_BotInitCvars();

View file

@ -10,6 +10,7 @@ snapshot pipeline delivers them to a spectator client.
*/
#include "server.h"
#include "lz4.h"
// ---------------------------------------------------------------
// File format
@ -50,9 +51,12 @@ snapshot pipeline delivers them to a spectator client.
//
#define SVDEMO_MAGIC (('S') | ('V' << 8) | ('D' << 16) | ('M' << 24))
#define SVDEMO_VERSION 1
#define SVDEMO_VERSION 2 // v2: optional LZ4 compression
#define SVDEMO_MAX_MAPNAME 64
// header flags
#define SVDEMO_FLAG_COMPRESSED 1 // per-frame data is LZ4 compressed
// ---------------------------------------------------------------
// State
// ---------------------------------------------------------------
@ -78,6 +82,7 @@ typedef struct {
// recording
fileHandle_t recordFile;
qboolean recording;
qboolean compressed; // LZ4 compression enabled
char *lastConfigstrings[MAX_CONFIGSTRINGS]; // for delta detection
svdEntityState_t prevEntities[MAX_GENTITIES]; // previous frame for delta
svdPlayerState_t prevPlayers[MAX_CLIENTS]; // previous frame player states
@ -123,6 +128,58 @@ static short SVD_ReadShort( fileHandle_t f ) {
return v;
}
// ---------------------------------------------------------------
// LZ4 block I/O: writes [uncompressed_size][compressed_size][data]
// ---------------------------------------------------------------
static void SVD_WriteBlock( fileHandle_t f, const byte *data, int len ) {
if ( demo.compressed && len > 0 ) {
int bound = LZ4_compressBound( len );
static byte compBuf[MAX_GENTITIES * 300];
int compLen;
compLen = LZ4_compress_default( (const char *)data, (char *)compBuf, len, bound );
if ( compLen > 0 ) {
SVD_WriteInt( f, len ); // original size
SVD_WriteInt( f, compLen ); // compressed size
FS_Write( compBuf, compLen, f );
return;
}
// fall through to uncompressed on failure
}
SVD_WriteInt( f, len ); // original size
SVD_WriteInt( f, 0 ); // 0 = not compressed
FS_Write( data, len, f );
}
static int SVD_ReadBlock( fileHandle_t f, byte *buf, int bufSize ) {
int origLen, compLen;
origLen = SVD_ReadInt( f );
compLen = SVD_ReadInt( f );
if ( origLen <= 0 || origLen > bufSize ) {
return -1;
}
if ( compLen > 0 ) {
// compressed
static byte compBuf[MAX_GENTITIES * 300];
if ( compLen > (int)sizeof(compBuf) ) {
return -1;
}
FS_Read( compBuf, compLen, f );
if ( LZ4_decompress_safe( (const char *)compBuf, (char *)buf, compLen, bufSize ) != origLen ) {
return -1;
}
} else {
// uncompressed
FS_Read( buf, origLen, f );
}
return origLen;
}
// ---------------------------------------------------------------
// Write header
// ---------------------------------------------------------------
@ -133,6 +190,7 @@ static void SVD_WriteHeader( fileHandle_t f ) {
SVD_WriteInt( f, SVDEMO_MAGIC );
SVD_WriteInt( f, SVDEMO_VERSION );
SVD_WriteInt( f, demo.compressed ? SVDEMO_FLAG_COMPRESSED : 0 );
SVD_WriteInt( f, sv_maxclients->integer );
SVD_WriteInt( f, sv_fps->integer );
@ -176,7 +234,6 @@ static void SVD_WriteFrame( fileHandle_t f ) {
short numChanges;
msg_t msg;
static byte msgBuf[MAX_GENTITIES * 300]; // worst case: all entities full write from baseline
int msgLen;
SVD_WriteInt( f, svs.time );
SVD_WriteShort( f, (short)sv.num_entities );
@ -245,10 +302,8 @@ static void SVD_WriteFrame( fileHandle_t f ) {
// end of entities marker
MSG_WriteBits( &msg, (MAX_GENTITIES - 1), GENTITYNUM_BITS );
// write compressed entity message to file
msgLen = msg.cursize;
SVD_WriteInt( f, msgLen );
FS_Write( msg.data, msgLen, f );
// write entity message to file (optionally LZ4 compressed)
SVD_WriteBlock( f, msg.data, msg.cursize );
// write player states (delta compressed)
{
@ -282,9 +337,7 @@ static void SVD_WriteFrame( fileHandle_t f ) {
MSG_WriteBits( &psmsg, MAX_CLIENTS - 1, 6 );
MSG_WriteBits( &psmsg, 0, 1 );
msgLen = psmsg.cursize;
SVD_WriteInt( f, msgLen );
FS_Write( psmsg.data, msgLen, f );
SVD_WriteBlock( f, psmsg.data, psmsg.cursize );
}
// configstring changes
@ -346,8 +399,10 @@ static qboolean SVD_StartRecording( const char *demoname ) {
return qfalse;
}
Com_Printf( "Recording server demo to %s\n", path );
Com_Printf( "Recording server demo to %s%s\n", path,
Cvar_VariableIntegerValue("svdemo_compress") ? " (LZ4)" : "" );
demo.recording = qtrue;
demo.compressed = Cvar_VariableIntegerValue("svdemo_compress") ? qtrue : qfalse;
// clear delta state for fresh recording
Com_Memset( demo.prevEntities, 0, sizeof(demo.prevEntities) );
@ -467,6 +522,11 @@ static qboolean SVD_ReadHeader( fileHandle_t f ) {
return qfalse;
}
{
int flags = SVD_ReadInt( f );
demo.compressed = ( flags & SVDEMO_FLAG_COMPRESSED ) ? qtrue : qfalse;
}
demo.playMaxClients = SVD_ReadInt( f );
demo.playFps = SVD_ReadInt( f );
FS_Read( demo.playMapName, SVDEMO_MAX_MAPNAME, f );
@ -523,7 +583,7 @@ static void SVD_ApplyConfigstrings( void ) {
static qboolean SVD_ReadFrame( fileHandle_t f ) {
int serverTime;
short numEnts, numChanges;
int i, entNum, msgLen;
int i, entNum, blockLen;
sharedEntity_t *ent;
msg_t msg;
static byte msgBuf[MAX_GENTITIES * 300];
@ -539,14 +599,13 @@ static qboolean SVD_ReadFrame( fileHandle_t f ) {
// time jumps that break client timeouts and heartbeats.
numEnts = SVD_ReadShort( f );
// read compressed message
msgLen = SVD_ReadInt( f );
if ( msgLen <= 0 || msgLen > (int)sizeof(msgBuf) ) {
// read entity message (optionally LZ4 compressed)
blockLen = SVD_ReadBlock( f, msgBuf, sizeof(msgBuf) );
if ( blockLen <= 0 ) {
return qfalse;
}
FS_Read( msgBuf, msgLen, f );
MSG_Init( &msg, msgBuf, sizeof(msgBuf) );
msg.cursize = msgLen;
msg.cursize = blockLen;
// clear all non-spectator entities
for ( i = 0; i < sv.num_entities; i++ ) {
@ -647,9 +706,8 @@ static qboolean SVD_ReadFrame( fileHandle_t f ) {
static byte psBuf[MAX_CLIENTS * 600]; // worst case: full playerState from baseline
int psMsgLen;
psMsgLen = SVD_ReadInt( f );
if ( psMsgLen > 0 && psMsgLen <= (int)sizeof(psBuf) ) {
FS_Read( psBuf, psMsgLen, f );
psMsgLen = SVD_ReadBlock( f, psBuf, sizeof(psBuf) );
if ( psMsgLen > 0 ) {
MSG_Init( &psmsg, psBuf, sizeof(psBuf) );
psmsg.cursize = psMsgLen;