MP4TrackId Mp4vCreator(MP4FileHandle mp4File, FILE* inFile, bool doEncrypt,
bool allowVariableFrameRate)
{
bool rc;
u_int8_t sampleBuffer[256 * 1024 * 2];
u_int8_t* pCurrentSample = sampleBuffer;
u_int32_t maxSampleSize = sizeof(sampleBuffer) / 2;
u_int32_t prevSampleSize = 0;
// the current syntactical object
// typically 1:1 with a sample
// but not always, i.e. non-VOP's
u_int8_t* pObj = pCurrentSample;
u_int32_t objSize;
u_int8_t objType;
// the current sample
MP4SampleId sampleId = 1;
MP4Timestamp currentSampleTime = 0;
// the last reference VOP
MP4SampleId refVopId = 1;
MP4Timestamp refVopTime = 0;
// track configuration info
u_int8_t videoProfileLevel = MPEG4_SP_L3;
u_int8_t timeBits = 15;
u_int16_t timeTicks = 30000;
u_int16_t frameDuration = 3000;
u_int16_t frameWidth = 320;
u_int16_t frameHeight = 240;
u_int32_t esConfigSize = 0;
int vopType = 0;
int prevVopType = 0;
bool foundVOSH = false, foundVO = false, foundVOL = false;
u_int32_t lastVopTimeIncrement = 0;
bool variableFrameRate = false;
bool lastFrame = false;
bool haveBframes = false;
mpeg4_frame_t *head = NULL, *tail = NULL;
// start reading objects until we get the first VOP
while (LoadNextObject(inFile, pObj, &objSize, &objType)) {
// guard against buffer overflow
if (pObj + objSize >= pCurrentSample + maxSampleSize) {
fprintf(stderr,
"%s: buffer overflow, invalid video stream?\n", ProgName);
return MP4_INVALID_TRACK_ID;
}
#ifdef DEBUG_MP4V
if (Verbosity & MP4_DETAILS_SAMPLE) {
printf("MP4V type %x size %u\n",
objType, objSize);
}
#endif
if (objType == MP4AV_MPEG4_VOSH_START) {
MP4AV_Mpeg4ParseVosh(pObj, objSize,
&videoProfileLevel);
foundVOSH = true;
} else if (objType == MP4AV_MPEG4_VO_START) {
foundVO = true;
} else if (objType == MP4AV_MPEG4_VOL_START) {
MP4AV_Mpeg4ParseVol(pObj, objSize,
&timeBits, &timeTicks, &frameDuration,
&frameWidth, &frameHeight);
foundVOL = true;
#ifdef DEBUG_MP4V
printf("ParseVol: timeBits %u timeTicks %u frameDuration %u\n",
timeBits, timeTicks, frameDuration);
#endif
} else if (foundVOL == true || objType == MP4AV_MPEG4_VOP_START) {
esConfigSize = pObj - pCurrentSample;
// ready to set up mp4 track
break;
}
/* XXX why do we need this if ?
* It looks like it will remove this object ... XXX */
// It does. On Purpose. wmay 6/2004
if (objType != MP4AV_MPEG4_USER_DATA_START) {
pObj += objSize;
}
}
if (foundVOSH == false) {
fprintf(stderr,
"%s: no VOSH header found in MPEG-4 video.\n"
"This can cause problems with players other than mp4player. \n",
ProgName);
} else {
if (VideoProfileLevelSpecified &&
videoProfileLevel != VideoProfileLevel) {
fprintf(stderr,
"%s: You have specified a different video profile level than was detected in the VOSH header\n"
"The level you specified was %d and %d was read from the VOSH\n",
ProgName, VideoProfileLevel, videoProfileLevel);
}
}
if (foundVO == false) {
fprintf(stderr,
"%s: No VO header found in mpeg-4 video.\n"
"This can cause problems with players other than mp4player\n",
ProgName);
}
if (foundVOL == false) {
fprintf(stderr,
"%s: fatal: No VOL header found in mpeg-4 video stream\n",
ProgName);
return MP4_INVALID_TRACK_ID;
}
// convert frame duration to canonical time scale
// note zero value for frame duration signals variable rate video
if (timeTicks == 0) {
timeTicks = 1;
}
u_int32_t mp4FrameDuration = 0;
if (VideoFrameRate) {
mp4FrameDuration = (u_int32_t)(((double)Mp4TimeScale) / VideoFrameRate);
} else if (frameDuration) {
VideoFrameRate = frameDuration;
VideoFrameRate /= timeTicks;
mp4FrameDuration = (Mp4TimeScale * frameDuration) / timeTicks;
} else {
if (allowVariableFrameRate == false ) {
fprintf(stderr,
"%s: variable rate video stream signalled,"
" please specify average frame rate with -r option\n"
" or --variable-frame-rate argument\n",
ProgName);
return MP4_INVALID_TRACK_ID;
}
variableFrameRate = true;
}
ismacryp_session_id_t ismaCrypSId;
mp4v2_ismacrypParams *icPp = (mp4v2_ismacrypParams *) malloc(sizeof(mp4v2_ismacrypParams));
memset(icPp, 0, sizeof(mp4v2_ismacrypParams));
// initialize ismacryp session if encrypting
if (doEncrypt) {
if (ismacrypInitSession(&ismaCrypSId,KeyTypeVideo) != 0) {
fprintf(stderr, "%s: could not initialize the ISMAcryp session\n",
ProgName);
return MP4_INVALID_TRACK_ID;
}
if (ismacrypGetScheme(ismaCrypSId, &(icPp->scheme_type)) != ismacryp_rc_ok) {
fprintf(stderr, "%s: could not get ismacryp scheme type. sid %d\n",
ProgName, ismaCrypSId);
ismacrypEndSession(ismaCrypSId);
return MP4_INVALID_TRACK_ID;
}
if (ismacrypGetSchemeVersion(ismaCrypSId, &(icPp->scheme_version)) != ismacryp_rc_ok) {
fprintf(stderr, "%s: could not get ismacryp scheme ver. sid %d\n",
ProgName, ismaCrypSId);
ismacrypEndSession(ismaCrypSId);
return MP4_INVALID_TRACK_ID;
}
if (ismacrypGetKMSUri(ismaCrypSId, &(icPp->kms_uri)) != ismacryp_rc_ok) {
fprintf(stderr, "%s: could not get ismacryp kms uri. sid %d\n",
ProgName, ismaCrypSId);
CHECK_AND_FREE(icPp->kms_uri);
ismacrypEndSession(ismaCrypSId);
return MP4_INVALID_TRACK_ID;
}
if ( ismacrypGetSelectiveEncryption(ismaCrypSId, &(icPp->selective_enc)) != ismacryp_rc_ok ) {
fprintf(stderr, "%s: could not get ismacryp selec enc. sid %d\n",
ProgName, ismaCrypSId);
ismacrypEndSession(ismaCrypSId);
return MP4_INVALID_TRACK_ID;
}
if (ismacrypGetKeyIndicatorLength(ismaCrypSId, &(icPp->key_ind_len)) != ismacryp_rc_ok) {
fprintf(stderr, "%s: could not get ismacryp key ind len. sid %d\n",
ProgName, ismaCrypSId);
ismacrypEndSession(ismaCrypSId);
return MP4_INVALID_TRACK_ID;
}
if (ismacrypGetIVLength(ismaCrypSId, &(icPp->iv_len)) != ismacryp_rc_ok) {
fprintf(stderr, "%s: could not get ismacryp iv len. sid %d\n",
ProgName, ismaCrypSId);
ismacrypEndSession(ismaCrypSId);
return MP4_INVALID_TRACK_ID;
}
}
// create the new video track
MP4TrackId trackId;
if (doEncrypt) {
trackId =
MP4AddEncVideoTrack(
mp4File,
Mp4TimeScale,
mp4FrameDuration,
frameWidth,
frameHeight,
icPp,
MP4_MPEG4_VIDEO_TYPE);
} else {
trackId =
MP4AddVideoTrack(
mp4File,
Mp4TimeScale,
mp4FrameDuration,
frameWidth,
frameHeight,
MP4_MPEG4_VIDEO_TYPE);
}
if (trackId == MP4_INVALID_TRACK_ID) {
fprintf(stderr,
"%s: can't create video track\n", ProgName);
return MP4_INVALID_TRACK_ID;
}
if (VideoProfileLevelSpecified) {
videoProfileLevel = VideoProfileLevel;
}
if (MP4GetNumberOfTracks(mp4File, MP4_VIDEO_TRACK_TYPE) == 1) {
MP4SetVideoProfileLevel(mp4File, videoProfileLevel);
}
printf("es config size is %d\n", esConfigSize);
if (esConfigSize) {
MP4SetTrackESConfiguration(mp4File, trackId,
pCurrentSample, esConfigSize);
// move past ES config, so it doesn't go into first sample
pCurrentSample += esConfigSize;
}
// Move the current frame to the beginning of the
// buffer
memmove(sampleBuffer, pCurrentSample, pObj - pCurrentSample + objSize);
pObj = sampleBuffer + (pObj - pCurrentSample);
pCurrentSample = sampleBuffer;
MP4Timestamp prevFrameTimestamp = 0;
// now process the rest of the video stream
while ( true ) {
if ( objType != MP4AV_MPEG4_VOP_START ) {
// keep it in the buffer until a VOP comes along
// Actually, do nothings, since we only want VOP
// headers in the stream - wmay 6/2004
//pObj += objSize;
} else { // we have VOP
u_int32_t sampleSize = (pObj + objSize) - pCurrentSample;
vopType = MP4AV_Mpeg4GetVopType(pObj, objSize);
mpeg4_frame_t *fr = MALLOC_STRUCTURE(mpeg4_frame_t);
if (head == NULL) {
head = tail = fr;
} else {
tail->next = fr;
tail = fr;
}
fr->vopType = vopType;
fr->frameTimestamp = currentSampleTime;
fr->next = NULL;
if ( variableFrameRate ) {
// variable frame rate: recalculate "mp4FrameDuration"
if ( lastFrame ) {
// last frame
mp4FrameDuration = Mp4TimeScale / timeTicks;
} else {
// not the last frame
u_int32_t vopTimeIncrement;
MP4AV_Mpeg4ParseVop(pObj, objSize, &vopType, timeBits, timeTicks, &vopTimeIncrement);
u_int32_t vopTime = vopTimeIncrement - lastVopTimeIncrement;
mp4FrameDuration = (Mp4TimeScale * vopTime) / timeTicks;
lastVopTimeIncrement = vopTimeIncrement % timeTicks;
}
}
if ( prevSampleSize > 0 ) { // not the first time
// fill sample data & length to write
u_int8_t* sampleData2Write = NULL;
u_int32_t sampleLen2Write = 0;
if ( doEncrypt ) {
if ( ismacrypEncryptSampleAddHeader(ismaCrypSId,
sampleSize,
sampleBuffer,
&sampleLen2Write,
&sampleData2Write) != 0 ) {
fprintf(stderr,
"%s: can't encrypt video sample and add header %u\n",
ProgName, sampleId);
}
} else {
sampleData2Write = sampleBuffer;
sampleLen2Write = prevSampleSize;
}
if (variableFrameRate == false) {
double now_calc;
now_calc = sampleId;
now_calc *= Mp4TimeScale;
now_calc /= VideoFrameRate;
MP4Timestamp now_ts = (MP4Timestamp)now_calc;
mp4FrameDuration = now_ts - prevFrameTimestamp;
prevFrameTimestamp = now_ts;
currentSampleTime = now_ts;
}
// Write the previous sample
rc = MP4WriteSample(mp4File, trackId,
sampleData2Write, sampleLen2Write,
mp4FrameDuration, 0, prevVopType == VOP_TYPE_I);
if ( doEncrypt && sampleData2Write ) {
// buffer allocated by encrypt function.
// must free it!
free(sampleData2Write);
}
if ( !rc ) {
fprintf(stderr,
"%s: can't write video frame %u\n",
ProgName, sampleId);
MP4DeleteTrack(mp4File, trackId);
return MP4_INVALID_TRACK_ID;
}
// deal with rendering time offsets
// that can occur when B frames are being used
// which is the case for all profiles except Simple Profile
haveBframes |= (prevVopType == VOP_TYPE_B);
if ( lastFrame ) {
// finish read frames
break;
}
sampleId++;
} // not the first time
currentSampleTime += mp4FrameDuration;
// Move the current frame to the beginning of the
// buffer
memmove(sampleBuffer, pCurrentSample, sampleSize);
prevSampleSize = sampleSize;
prevVopType = vopType;
// reset pointers
pObj = pCurrentSample = sampleBuffer + sampleSize;
} // we have VOP
// load next object from bitstream
if (!LoadNextObject(inFile, pObj, &objSize, &objType)) {
if (objType != MP4AV_MPEG4_VOP_START)
break;
lastFrame = true;
objSize = 0;
continue;
}
// guard against buffer overflow
if (pObj + objSize >= pCurrentSample + maxSampleSize) {
fprintf(stderr,
"%s: buffer overflow, invalid video stream?\n", ProgName);
MP4DeleteTrack(mp4File, trackId);
return MP4_INVALID_TRACK_ID;
}
#ifdef DEBUG_MP4V
if (Verbosity & MP4_DETAILS_SAMPLE) {
printf("MP4V type %x size %u\n",
objType, objSize);
}
#endif
}
bool doRenderingOffset = false;
switch (videoProfileLevel) {
case MPEG4_SP_L0:
case MPEG4_SP_L1:
case MPEG4_SP_L2:
case MPEG4_SP_L3:
break;
default:
doRenderingOffset = true;
break;
}
if (doRenderingOffset && haveBframes) {
// only generate ctts (with rendering offset for I, P frames) when
// we need one. We saved all the frames types and timestamps above -
// we can't use MP4ReadSample, because the end frames might not have
// been written
refVopId = 1;
refVopTime = 0;
MP4SampleId maxSamples = MP4GetTrackNumberOfSamples(mp4File, trackId);
// start with sample 2 - we know the first one is a I frame
mpeg4_frame_t *fr = head->next; // skip the first one
for (MP4SampleId ix = 2; ix <= maxSamples; ix++) {
if (fr->vopType != VOP_TYPE_B) {
#ifdef DEBUG_MP4V_TS
printf("sample %u %u renderingOffset "U64"\n",
refVopId, fr->vopType, fr->frameTimestamp - refVopTime);
#endif
MP4SetSampleRenderingOffset(mp4File, trackId, refVopId,
fr->frameTimestamp - refVopTime);
refVopId = ix;
refVopTime = fr->frameTimestamp;
}
fr = fr->next;
}
#ifdef DEBUG_MP4V_TS
printf("sample %u %u renderingOffset "U64"\n",
refVopId, fr->vopType, fr->frameTimestamp - refVopTime);
#endif
MP4SetSampleRenderingOffset(mp4File, trackId, refVopId,
fr->frameTimestamp - refVopTime);
}
while (head != NULL) {
tail = head->next;
free(head);
head = tail;
}
// terminate session if encrypting
if (doEncrypt) {
if (ismacrypEndSession(ismaCrypSId) != 0) {
fprintf(stderr,
"%s: could not end the ISMAcryp session\n",
ProgName);
}
}
return trackId;
}
static int look_and_parse_vol (xvid_codec_t *xvid,
uint8_t *bufptr,
uint32_t len)
{
uint8_t *volptr;
uint32_t vollen;
int ret;
volptr = MP4AV_Mpeg4FindVol(bufptr, len);
if (volptr == NULL) {
return -1;
}
vollen = len - (volptr - bufptr);
uint8_t timeBits;
uint16_t timeTicks, dur, width, height;
uint8_t aspect_ratio, aspect_ratio_w, aspect_ratio_h;
if (MP4AV_Mpeg4ParseVol(volptr,
vollen,
&timeBits,
&timeTicks,
&dur,
&width,
&height,
&aspect_ratio,
&aspect_ratio_w,
&aspect_ratio_h) == false) {
return -1;
}
xvid_message(LOG_DEBUG, "xvid", "aspect ratio %x %d %d",
aspect_ratio, aspect_ratio_w, aspect_ratio_h);
// Get the VO/VOL header. If we fail, set the bytestream back
ret = 0;
XVID_DEC_PARAM param;
param.width = width;
param.height = height;
ret = xvid_decore(NULL, XVID_DEC_CREATE,
¶m, NULL);
if (ret != XVID_ERR_OK) {
return -1;
}
double ar = 0.0;
switch (aspect_ratio) {
default:
aspect_ratio_h = 0;
break;
case 2:
aspect_ratio_w = 12;
aspect_ratio_h = 11;
break;
case 3:
aspect_ratio_w = 10;
aspect_ratio_h = 11;
break;
case 4:
aspect_ratio_w = 16;
aspect_ratio_h = 11;
break;
case 5:
aspect_ratio_w = 40;
aspect_ratio_h = 33;
break;
case 0xf:
break;
}
if (aspect_ratio_h != 0) {
ar = (double)aspect_ratio_w;
ar *= (double) param.width;
ar /= (double)aspect_ratio_h;
ar /= (double)param.height;
}
xvid->m_xvid_handle = param.handle;
xvid->m_vft->video_configure(xvid->m_ifptr,
param.width,
param.height,
VIDEO_FORMAT_YUV,
ar);
// we need to then run the VOL through the decoder.
XVID_DEC_FRAME frame;
XVID_DEC_PICTURE decpict;
frame.bitstream = (void *)volptr;
frame.length = vollen;
frame.colorspace = XVID_CSP_USER;
frame.image = &decpict;
ret = xvid_decore(xvid->m_xvid_handle, XVID_DEC_DECODE, &frame, NULL);
xvid_message(LOG_NOTICE, "xvidif", "decoded vol ret %d", ret);
return ret == XVID_ERR_OK ? 0 : -1;
}
static codec_data_t *ffmpeg_create (const char *stream_type,
const char *compressor,
int type,
int profile,
format_list_t *media_fmt,
video_info_t *vinfo,
const uint8_t *userdata,
uint32_t ud_size,
video_vft_t *vft,
void *ifptr)
{
ffmpeg_codec_t *ffmpeg;
ffmpeg = MALLOC_STRUCTURE(ffmpeg_codec_t);
memset(ffmpeg, 0, sizeof(*ffmpeg));
ffmpeg->m_vft = vft;
ffmpeg->m_ifptr = ifptr;
avcodec_init();
avcodec_register_all();
av_log_set_level(AV_LOG_QUIET);
ffmpeg->m_codecId = ffmpeg_find_codec(stream_type, compressor, type,
profile, media_fmt, userdata, ud_size);
// must have a codecID - we checked it earlier
ffmpeg->m_codec = avcodec_find_decoder(ffmpeg->m_codecId);
ffmpeg->m_c = avcodec_alloc_context();
ffmpeg->m_picture = avcodec_alloc_frame();
bool open_codec = true;
bool run_userdata = false;
bool free_userdata = false;
switch (ffmpeg->m_codecId) {
case CODEC_ID_MJPEG:
break;
case CODEC_ID_H264:
// need to find height and width
if (media_fmt != NULL && media_fmt->fmt_param != NULL) {
userdata = h264_sdp_parse_sprop_param_sets(media_fmt->fmt_param,
&ud_size,
ffmpeg->m_vft->log_msg);
if (userdata != NULL) free_userdata = true;
ffmpeg_message(LOG_DEBUG, "ffmpeg", "sprop len %d", ud_size);
}
if (ud_size > 0) {
ffmpeg_message(LOG_DEBUG, "ffmpeg", "userdata len %d", ud_size);
open_codec = ffmpeg_find_h264_size(ffmpeg, userdata, ud_size);
ffmpeg_message(LOG_DEBUG, "ffmpeg", "open codec is %d", open_codec);
run_userdata = true;
} else {
open_codec = false;
}
break;
case CODEC_ID_MPEG4: {
fmtp_parse_t *fmtp = NULL;
open_codec = false;
if (media_fmt != NULL) {
fmtp = parse_fmtp_for_mpeg4(media_fmt->fmt_param,
ffmpeg->m_vft->log_msg);
if (fmtp->config_binary != NULL) {
userdata = fmtp->config_binary;
ud_size = fmtp->config_binary_len;
fmtp->config_binary = NULL;
free_userdata = true;
}
}
if (ud_size > 0) {
uint8_t *vol = MP4AV_Mpeg4FindVol((uint8_t *)userdata, ud_size);
u_int8_t TimeBits;
u_int16_t TimeTicks;
u_int16_t FrameDuration;
u_int16_t FrameWidth;
u_int16_t FrameHeight;
u_int8_t aspectRatioDefine;
u_int8_t aspectRatioWidth;
u_int8_t aspectRatioHeight;
if (vol) {
if (MP4AV_Mpeg4ParseVol(vol,
ud_size - (vol - userdata),
&TimeBits,
&TimeTicks,
&FrameDuration,
&FrameWidth,
&FrameHeight,
&aspectRatioDefine,
&aspectRatioWidth,
&aspectRatioHeight)) {
ffmpeg->m_c->width = FrameWidth;
ffmpeg->m_c->height = FrameHeight;
open_codec = true;
run_userdata = true;
}
}
}
if (fmtp != NULL) {
free_fmtp_parse(fmtp);
}
}
break;
case CODEC_ID_SVQ3:
ffmpeg->m_c->extradata = (void *)userdata;
ffmpeg->m_c->extradata_size = ud_size;
if (vinfo != NULL) {
ffmpeg->m_c->width = vinfo->width;
ffmpeg->m_c->height = vinfo->height;
}
break;
default:
break;
}
if (open_codec) {
if (avcodec_open(ffmpeg->m_c, ffmpeg->m_codec) < 0) {
ffmpeg_message(LOG_CRIT, "ffmpeg", "failed to open codec");
return NULL;
}
ffmpeg_message(LOG_DEBUG, "ffmpeg", "pixel format is %d",
ffmpeg->m_c->pix_fmt);
ffmpeg->m_codec_opened = true;
if (run_userdata) {
uint32_t offset = 0;
do {
int got_picture;
offset += avcodec_decode_video(ffmpeg->m_c,
ffmpeg->m_picture,
&got_picture,
(uint8_t *)userdata + offset,
ud_size - offset);
} while (offset < ud_size);
}
}
if (free_userdata) {
CHECK_AND_FREE(userdata);
}
ffmpeg->m_did_pause = 1;
return ((codec_data_t *)ffmpeg);
}
static int look_for_vol (xvid_codec_t *xvid,
uint8_t *bufptr,
uint32_t len)
{
uint8_t *volptr;
int vollen;
int ret;
volptr = MP4AV_Mpeg4FindVol(bufptr, len);
if (volptr == NULL) {
return -1 ;
}
vollen = len - (volptr - bufptr);
uint8_t timeBits;
uint16_t timeTicks, dur, width, height;
uint8_t aspect_ratio, aspect_ratio_w, aspect_ratio_h;
if (MP4AV_Mpeg4ParseVol(volptr,
vollen,
&timeBits,
&timeTicks,
&dur,
&width,
&height,
&aspect_ratio,
&aspect_ratio_w,
&aspect_ratio_h) == false) {
return -1;
}
xvid_message(LOG_DEBUG, "xvid", "aspect ratio %x %d %d",
aspect_ratio, aspect_ratio_w, aspect_ratio_h);
// Get the VO/VOL header. If we fail, set the bytestream back
xvid_dec_create_t create;
create.version = XVID_VERSION;
create.width = width;
create.height = height;
ret = xvid_decore(NULL, XVID_DEC_CREATE,
&create, NULL);
double ar = 0.0;
switch (aspect_ratio) {
default:
aspect_ratio_h = 0;
break;
case 2:
aspect_ratio_w = 12;
aspect_ratio_h = 11;
break;
case 3:
aspect_ratio_w = 10;
aspect_ratio_h = 11;
break;
case 4:
aspect_ratio_w = 16;
aspect_ratio_h = 11;
break;
case 5:
aspect_ratio_w = 40;
aspect_ratio_h = 33;
break;
case 0xf:
break;
}
if (aspect_ratio_h != 0) {
ar = (double)aspect_ratio_w;
ar *= (double) create.width;
ar /= (double)aspect_ratio_h;
ar /= (double)create.height;
}
xvid->m_xvid_handle = create.handle;
xvid->m_vft->video_configure(xvid->m_ifptr,
create.width,
create.height,
VIDEO_FORMAT_YUV,
ar);
// we need to then run the VOL through the decoder.
xvid_dec_frame_t dec;
xvid_dec_stats_t stats;
do {
dec.version = XVID_VERSION;
dec.bitstream = volptr;
dec.length = vollen;
dec.output.csp = XVID_CSP_INTERNAL;
stats.version = XVID_VERSION;
ret = xvid_decore(xvid->m_xvid_handle,
XVID_DEC_DECODE,
&dec,
&stats);
if (ret < 0) {
xvid_message(LOG_NOTICE, "xvidif", "decoded vol ret %d", ret);
}
if (ret < 0 || ret > vollen) {
vollen = 0;
} else {
vollen -= ret;
volptr += ret;
}
// we could check for vol changes, etc here, if we wanted.
} while (vollen > 4 && stats.type == 0);
return 0;
}
