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Fix overwriting of 7-bit PictureID when doing VP8 simulcast #3121

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merged 3 commits into from
Dec 21, 2022
Merged

Fix overwriting of 7-bit PictureID when doing VP8 simulcast #3121

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fb96a36
Fix overwriting of 7-bit PictureID when doing VP8 simulcast
lminiero Dec 13, 2022
49bf4b4
Updated RTP fuzzer after the janus_vp8_parse_descriptor signature change
lminiero Dec 13, 2022
40147f8
Fixed 'math' on PictureID
lminiero Dec 13, 2022
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3 changes: 2 additions & 1 deletion fuzzers/rtp_fuzzer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -92,12 +92,13 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
janus_h264_is_keyframe(payload, plen);

/* VP8 targets */
gboolean m = FALSE;
uint16_t picid = 0;
uint8_t tlzi = 0, tid = 0, ybit = 0, keyidx = 0;
janus_vp8_simulcast_context vp8_context;
memset(&vp8_context, 0, sizeof(janus_vp8_simulcast_context));
janus_vp8_is_keyframe(payload, plen);
janus_vp8_parse_descriptor(payload, plen, &picid, &tlzi, &tid, &ybit, &keyidx);
janus_vp8_parse_descriptor(payload, plen, &m, &picid, &tlzi, &tid, &ybit, &keyidx);
janus_vp8_simulcast_descriptor_update(copy_payload, plen, &vp8_context, TRUE);

/* VP9 targets */
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3 changes: 2 additions & 1 deletion src/rtp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1196,12 +1196,13 @@ gboolean janus_rtp_simulcasting_context_process_rtp(janus_rtp_simulcasting_conte
/* Temporal layers are only available for VP8, so don't do anything else for other codecs */
if(vcodec == JANUS_VIDEOCODEC_VP8) {
/* Check if there's any temporal scalability to take into account */
gboolean m = FALSE;
uint16_t picid = 0;
uint8_t tlzi = 0;
uint8_t tid = 0;
uint8_t ybit = 0;
uint8_t keyidx = 0;
if(janus_vp8_parse_descriptor(payload, plen, &picid, &tlzi, &tid, &ybit, &keyidx) == 0) {
if(janus_vp8_parse_descriptor(payload, plen, &m, &picid, &tlzi, &tid, &ybit, &keyidx) == 0) {
//~ JANUS_LOG(LOG_WARN, "%"SCNu16", %u, %u, %u, %u\n", picid, tlzi, tid, ybit, keyidx);
if(context->templayer != context->templayer_target && tid == context->templayer_target) {
/* FIXME We should be smarter in deciding when to switch */
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20 changes: 15 additions & 5 deletions src/utils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -904,7 +904,7 @@ gboolean janus_h265_is_keyframe(const char *buffer, int len) {
}

int janus_vp8_parse_descriptor(char *buffer, int len,
uint16_t *picid, uint8_t *tl0picidx, uint8_t *tid, uint8_t *y, uint8_t *keyidx) {
gboolean *m, uint16_t *picid, uint8_t *tl0picidx, uint8_t *tid, uint8_t *y, uint8_t *keyidx) {
if(!buffer || len < 6)
return -1;
if(picid)
Expand Down Expand Up @@ -939,6 +939,8 @@ int janus_vp8_parse_descriptor(char *buffer, int len,
partpicid = (wholepicid & 0x7FFF);
buffer++;
}
if(m)
*m = (mbit ? TRUE : FALSE);
if(picid)
*picid = partpicid;
}
Expand All @@ -964,7 +966,7 @@ int janus_vp8_parse_descriptor(char *buffer, int len,
return 0;
}

static int janus_vp8_replace_descriptor(char *buffer, int len, uint16_t picid, uint8_t tl0picidx) {
static int janus_vp8_replace_descriptor(char *buffer, int len, gboolean m, uint16_t picid, uint8_t tl0picidx) {
if(!buffer || len < 6)
return -1;
uint8_t vp8pd = *buffer;
Expand All @@ -982,7 +984,7 @@ static int janus_vp8_replace_descriptor(char *buffer, int len, uint16_t picid, u
buffer++;
vp8pd = *buffer;
uint8_t mbit = (vp8pd & 0x80);
if(!mbit) {
if(!mbit || !m) {
*buffer = picid;
} else {
uint16_t wholepicid = htons(picid);
Expand Down Expand Up @@ -1019,13 +1021,14 @@ void janus_vp8_simulcast_context_reset(janus_vp8_simulcast_context *context) {
void janus_vp8_simulcast_descriptor_update(char *buffer, int len, janus_vp8_simulcast_context *context, gboolean switched) {
if(!buffer || len < 0)
return;
gboolean m = FALSE;
uint16_t picid = 0;
uint8_t tlzi = 0;
uint8_t tid = 0;
uint8_t ybit = 0;
uint8_t keyidx = 0;
/* Parse the identifiers in the VP8 payload descriptor */
if(janus_vp8_parse_descriptor(buffer, len, &picid, &tlzi, &tid, &ybit, &keyidx) < 0)
if(janus_vp8_parse_descriptor(buffer, len, &m, &picid, &tlzi, &tid, &ybit, &keyidx) < 0)
return;
if(switched) {
context->base_picid_prev = context->last_picid;
Expand All @@ -1034,9 +1037,16 @@ void janus_vp8_simulcast_descriptor_update(char *buffer, int len, janus_vp8_simu
context->base_tlzi = tlzi;
}
context->last_picid = (picid-context->base_picid)+context->base_picid_prev+1;
if(!m && context->last_picid > 127) {
context->last_picid -= 128;
if(context->last_picid > 127)
context->last_picid = 0;
} else if(m && context->last_picid > 32767) {
context->last_picid -= 32768;
}
context->last_tlzi = (tlzi-context->base_tlzi)+context->base_tlzi_prev+1;
/* Overwrite the values in the VP8 payload descriptors with the ones we have */
janus_vp8_replace_descriptor(buffer, len, context->last_picid, context->last_tlzi);
janus_vp8_replace_descriptor(buffer, len, m, context->last_picid, context->last_tlzi);
}

/* Helper method to parse a VP9 RTP video frame and get some SVC-related info:
Expand Down
3 changes: 2 additions & 1 deletion src/utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -356,14 +356,15 @@ void janus_vp8_simulcast_context_reset(janus_vp8_simulcast_context *context);
/*! \brief Helper method to parse a VP8 payload descriptor for useful info (e.g., when simulcasting)
* @param[in] buffer The RTP payload to process
* @param[in] len The length of the RTP payload
* @param[out] m Whether the Picture ID is 15 bit or 7 bit
* @param[out] picid The Picture ID
* @param[out] tl0picidx Temporal level zero index
* @param[out] tid Temporal-layer index
* @param[out] y Layer sync bit
* @param[out] keyidx Temporal key frame index
* @returns 0 in case of success, a negative integer otherwise */
int janus_vp8_parse_descriptor(char *buffer, int len,
uint16_t *picid, uint8_t *tl0picidx, uint8_t *tid, uint8_t *y, uint8_t *keyidx);
gboolean *m, uint16_t *picid, uint8_t *tl0picidx, uint8_t *tid, uint8_t *y, uint8_t *keyidx);

/*! \brief Use the context info to update the RTP header of a packet, if needed
* @param[in] buffer The RTP payload to process
Expand Down