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libobs: Implement H.264/HEVC priority parsing 

Parsing priority while serializing/discarding packet data is too gross.
master
jpark37 2022-08-01 08:15:29 -07:00
parent c2122b0916
commit 0e5420750b
4 changed files with 101 additions and 33 deletions
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61
libobs/obs-avc.c
View File

@ -51,6 +51,24 @@ const uint8_t *obs_avc_find_startcode(const uint8_t *p, const uint8_t *end)
return obs_nal_find_startcode(p, end);
}
static int compute_avc_keyframe_priority(const uint8_t *nal_start,
bool *is_keyframe, int priority)
{
const int type = nal_start[0] & 0x1F;
switch (type) {
case OBS_NAL_SLICE:
if (priority < OBS_NAL_PRIORITY_HIGH)
priority = OBS_NAL_PRIORITY_HIGH;
break;
case OBS_NAL_SLICE_IDR:
*is_keyframe = true;
priority = OBS_NAL_PRIORITY_HIGHEST;
}
return priority;
}
static void serialize_avc_data(struct serializer *s, const uint8_t *data,
size_t size, bool *is_keyframe, int *priority)
{
@ -63,23 +81,14 @@ static void serialize_avc_data(struct serializer *s, const uint8_t *data,
if (nal_start == end)
break;
const int type = nal_start[0] & 0x1F;
switch (type) {
case OBS_NAL_SLICE:
if (*priority < OBS_NAL_PRIORITY_HIGH)
*priority = OBS_NAL_PRIORITY_HIGH;
break;
case OBS_NAL_SLICE_IDR:
*is_keyframe = true;
*priority = OBS_NAL_PRIORITY_HIGHEST;
}
*priority = compute_avc_keyframe_priority(
nal_start, is_keyframe, *priority);
const uint8_t *const nal_end =
obs_nal_find_startcode(nal_start, end);
const size_t size = nal_end - nal_start;
s_wb32(s, (uint32_t)size);
s_write(s, nal_start, size);
const size_t nal_size = nal_end - nal_start;
s_wb32(s, (uint32_t)nal_size);
s_write(s, nal_start, nal_size);
nal_start = nal_end;
}
}
@ -103,6 +112,30 @@ void obs_parse_avc_packet(struct encoder_packet *avc_packet,
avc_packet->drop_priority = avc_packet->priority;
}
int obs_parse_avc_packet_priority(const struct encoder_packet *packet)
{
int priority = packet->priority;
const uint8_t *const data = packet->data;
const uint8_t *const end = data + packet->size;
const uint8_t *nal_start = obs_nal_find_startcode(data, end);
while (true) {
while (nal_start < end && !*(nal_start++))
;
if (nal_start == end)
break;
bool unused;
priority = compute_avc_keyframe_priority(nal_start, &unused,
priority);
nal_start = obs_nal_find_startcode(nal_start, end);
}
return priority;
}
static inline bool has_start_code(const uint8_t *data)
{
if (data[0] != 0 || data[1] != 0)

1
libobs/obs-avc.h
View File

@ -46,6 +46,7 @@ EXPORT const uint8_t *obs_avc_find_startcode(const uint8_t *p,
const uint8_t *end);
EXPORT void obs_parse_avc_packet(struct encoder_packet *avc_packet,
const struct encoder_packet *src);
EXPORT int obs_parse_avc_packet_priority(const struct encoder_packet *packet);
EXPORT size_t obs_parse_avc_header(uint8_t **header, const uint8_t *data,
size_t size);
EXPORT void obs_extract_avc_headers(const uint8_t *packet, size_t size,

71
libobs/obs-hevc.c
View File

@ -90,6 +90,29 @@ bool obs_hevc_keyframe(const uint8_t *data, size_t size)
return false;
}
static int compute_hevc_keyframe_priority(const uint8_t *nal_start,
bool *is_keyframe, int priority)
{
// HEVC contains NAL unit specifier at [6..1] bits of
// the byte next to the startcode 0x000001
const int type = (nal_start[0] & 0x7F) >> 1;
// Mark IDR slices as key-frames and set them to highest
// priority if needed. Assume other slices are non-key
// frames and set their priority as high
if (type >= OBS_HEVC_NAL_BLA_W_LP &&
type <= OBS_HEVC_NAL_RSV_IRAP_VCL23) {
*is_keyframe = 1;
priority = OBS_NAL_PRIORITY_HIGHEST;
} else if (type >= OBS_HEVC_NAL_TRAIL_N &&
type <= OBS_HEVC_NAL_RASL_R) {
if (priority < OBS_NAL_PRIORITY_HIGH)
priority = OBS_NAL_PRIORITY_HIGH;
}
return priority;
}
static void serialize_hevc_data(struct serializer *s, const uint8_t *data,
size_t size, bool *is_keyframe, int *priority)
{
@ -102,28 +125,14 @@ static void serialize_hevc_data(struct serializer *s, const uint8_t *data,
if (nal_start == end)
break;
// HEVC contains NAL unit specifier at [6..1] bits of
// the byte next to the startcode 0x000001
const int type = (nal_start[0] & 0x7F) >> 1;
// Mark IDR slices as key-frames and set them to highest
// priority if needed. Assume other slices are non-key
// frames and set their priority as high
if (type >= OBS_HEVC_NAL_BLA_W_LP &&
type <= OBS_HEVC_NAL_RSV_IRAP_VCL23) {
*is_keyframe = 1;
*priority = OBS_NAL_PRIORITY_HIGHEST;
} else if (type >= OBS_HEVC_NAL_TRAIL_N &&
type <= OBS_HEVC_NAL_RASL_R) {
if (*priority < OBS_NAL_PRIORITY_HIGH)
*priority = OBS_NAL_PRIORITY_HIGH;
}
*priority = compute_hevc_keyframe_priority(
nal_start, is_keyframe, *priority);
const uint8_t *const nal_end =
obs_nal_find_startcode(nal_start, end);
const size_t size = nal_end - nal_start;
s_wb32(s, (uint32_t)size);
s_write(s, nal_start, size);
const size_t nal_size = nal_end - nal_start;
s_wb32(s, (uint32_t)nal_size);
s_write(s, nal_start, nal_size);
nal_start = nal_end;
}
}
@ -147,6 +156,30 @@ void obs_parse_hevc_packet(struct encoder_packet *hevc_packet,
hevc_packet->drop_priority = hevc_packet->priority;
}
int obs_parse_hevc_packet_priority(const struct encoder_packet *packet)
{
int priority = packet->priority;
const uint8_t *const data = packet->data;
const uint8_t *const end = data + packet->size;
const uint8_t *nal_start = obs_nal_find_startcode(data, end);
while (true) {
while (nal_start < end && !*(nal_start++))
;
if (nal_start == end)
break;
bool unused;
priority = compute_hevc_keyframe_priority(nal_start, &unused,
priority);
nal_start = obs_nal_find_startcode(nal_start, end);
}
return priority;
}
void obs_extract_hevc_headers(const uint8_t *packet, size_t size,
uint8_t **new_packet_data,
size_t *new_packet_size, uint8_t **header_data,

1
libobs/obs-hevc.h
View File

@ -28,6 +28,7 @@ struct encoder_packet;
EXPORT bool obs_hevc_keyframe(const uint8_t *data, size_t size);
EXPORT void obs_parse_hevc_packet(struct encoder_packet *hevc_packet,
const struct encoder_packet *src);
EXPORT int obs_parse_hevc_packet_priority(const struct encoder_packet *packet);
EXPORT void obs_extract_hevc_headers(const uint8_t *packet, size_t size,
uint8_t **new_packet_data,
size_t *new_packet_size,