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Mp4: mp4_start_key_frame directive.

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The directive enables including all frames from start time to the most recent
key frame in the result.  Those frames are removed from presentation timeline
using mp4 edit lists.

Edit lists are currently supported by popular players and browsers such as
Chrome, Safari, QuickTime and ffmpeg.  Among those not supporting them properly
is Firefox[1].

Based on a patch by Tracey Jaquith, Internet Archive.

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1735300
This commit is contained in:
Roman Arutyunyan 2021-10-28 14:14:25 +03:00
parent 27cdfe30f7
commit 7927071ee2
1 changed files with 194 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

221
src/http/modules/ngx_http_mp4_module.c
View File

@ -11,31 +11,33 @@
#define NGX_HTTP_MP4_TRAK_ATOM 0
#define NGX_HTTP_MP4_TKHD_ATOM 1
#define NGX_HTTP_MP4_MDIA_ATOM 2
#define NGX_HTTP_MP4_MDHD_ATOM 3
#define NGX_HTTP_MP4_HDLR_ATOM 4
#define NGX_HTTP_MP4_MINF_ATOM 5
#define NGX_HTTP_MP4_VMHD_ATOM 6
#define NGX_HTTP_MP4_SMHD_ATOM 7
#define NGX_HTTP_MP4_DINF_ATOM 8
#define NGX_HTTP_MP4_STBL_ATOM 9
#define NGX_HTTP_MP4_STSD_ATOM 10
#define NGX_HTTP_MP4_STTS_ATOM 11
#define NGX_HTTP_MP4_STTS_DATA 12
#define NGX_HTTP_MP4_STSS_ATOM 13
#define NGX_HTTP_MP4_STSS_DATA 14
#define NGX_HTTP_MP4_CTTS_ATOM 15
#define NGX_HTTP_MP4_CTTS_DATA 16
#define NGX_HTTP_MP4_STSC_ATOM 17
#define NGX_HTTP_MP4_STSC_START 18
#define NGX_HTTP_MP4_STSC_DATA 19
#define NGX_HTTP_MP4_STSC_END 20
#define NGX_HTTP_MP4_STSZ_ATOM 21
#define NGX_HTTP_MP4_STSZ_DATA 22
#define NGX_HTTP_MP4_STCO_ATOM 23
#define NGX_HTTP_MP4_STCO_DATA 24
#define NGX_HTTP_MP4_CO64_ATOM 25
#define NGX_HTTP_MP4_CO64_DATA 26
#define NGX_HTTP_MP4_EDTS_ATOM 2
#define NGX_HTTP_MP4_ELST_ATOM 3
#define NGX_HTTP_MP4_MDIA_ATOM 4
#define NGX_HTTP_MP4_MDHD_ATOM 5
#define NGX_HTTP_MP4_HDLR_ATOM 6
#define NGX_HTTP_MP4_MINF_ATOM 7
#define NGX_HTTP_MP4_VMHD_ATOM 8
#define NGX_HTTP_MP4_SMHD_ATOM 9
#define NGX_HTTP_MP4_DINF_ATOM 10
#define NGX_HTTP_MP4_STBL_ATOM 11
#define NGX_HTTP_MP4_STSD_ATOM 12
#define NGX_HTTP_MP4_STTS_ATOM 13
#define NGX_HTTP_MP4_STTS_DATA 14
#define NGX_HTTP_MP4_STSS_ATOM 15
#define NGX_HTTP_MP4_STSS_DATA 16
#define NGX_HTTP_MP4_CTTS_ATOM 17
#define NGX_HTTP_MP4_CTTS_DATA 18
#define NGX_HTTP_MP4_STSC_ATOM 19
#define NGX_HTTP_MP4_STSC_START 20
#define NGX_HTTP_MP4_STSC_DATA 21
#define NGX_HTTP_MP4_STSC_END 22
#define NGX_HTTP_MP4_STSZ_ATOM 23
#define NGX_HTTP_MP4_STSZ_DATA 24
#define NGX_HTTP_MP4_STCO_ATOM 25
#define NGX_HTTP_MP4_STCO_DATA 26
#define NGX_HTTP_MP4_CO64_ATOM 27
#define NGX_HTTP_MP4_CO64_DATA 28
#define NGX_HTTP_MP4_LAST_ATOM NGX_HTTP_MP4_CO64_DATA
@ -43,6 +45,7 @@
typedef struct {
size_t buffer_size;
size_t max_buffer_size;
ngx_flag_t start_key_frame;
} ngx_http_mp4_conf_t;
@ -53,6 +56,25 @@ typedef struct {
} ngx_mp4_stsc_entry_t;
typedef struct {
u_char size[4];
u_char name[4];
} ngx_mp4_edts_atom_t;
typedef struct {
u_char size[4];
u_char name[4];
u_char version[1];
u_char flags[3];
u_char entries[4];
u_char duration[8];
u_char media_time[8];
u_char media_rate[2];
u_char reserved[2];
} ngx_mp4_elst_atom_t;
typedef struct {
uint32_t timescale;
uint32_t time_to_sample_entries;
@ -71,6 +93,8 @@ typedef struct {
uint64_t start_chunk_samples_size;
uint64_t end_chunk_samples_size;
uint64_t duration;
uint64_t prefix;
uint64_t movie_duration;
off_t start_offset;
off_t end_offset;
@ -86,6 +110,8 @@ typedef struct {
ngx_buf_t trak_atom_buf;
ngx_buf_t tkhd_atom_buf;
ngx_buf_t edts_atom_buf;
ngx_buf_t elst_atom_buf;
ngx_buf_t mdia_atom_buf;
ngx_buf_t mdhd_atom_buf;
ngx_buf_t hdlr_atom_buf;
@ -112,6 +138,8 @@ typedef struct {
ngx_buf_t co64_atom_buf;
ngx_buf_t co64_data_buf;
ngx_mp4_edts_atom_t edts_atom;
ngx_mp4_elst_atom_t elst_atom;
ngx_mp4_stsc_entry_t stsc_start_chunk_entry;
ngx_mp4_stsc_entry_t stsc_end_chunk_entry;
} ngx_http_mp4_trak_t;
@ -187,6 +215,14 @@ typedef struct {
((u_char *) (p))[6] = n3; \
((u_char *) (p))[7] = n4
#define ngx_mp4_get_16value(p) \
( ((uint16_t) ((u_char *) (p))[0] << 8) \
+ ( ((u_char *) (p))[1]) )
#define ngx_mp4_set_16value(p, n) \
((u_char *) (p))[0] = (u_char) ((n) >> 8); \
((u_char *) (p))[1] = (u_char) (n)
#define ngx_mp4_get_32value(p) \
( ((uint32_t) ((u_char *) (p))[0] << 24) \
+ ( ((u_char *) (p))[1] << 16) \
@ -270,6 +306,8 @@ static ngx_int_t ngx_http_mp4_read_smhd_atom(ngx_http_mp4_file_t *mp4,
uint64_t atom_data_size);
static ngx_int_t ngx_http_mp4_read_stbl_atom(ngx_http_mp4_file_t *mp4,
uint64_t atom_data_size);
static void ngx_http_mp4_update_edts_atom(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak);
static void ngx_http_mp4_update_stbl_atom(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak);
static ngx_int_t ngx_http_mp4_read_stsd_atom(ngx_http_mp4_file_t *mp4,
@ -280,6 +318,8 @@ static ngx_int_t ngx_http_mp4_update_stts_atom(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak);
static ngx_int_t ngx_http_mp4_crop_stts_data(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak, ngx_uint_t start);
static uint32_t ngx_http_mp4_seek_key_frame(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak, uint32_t start_sample);
static ngx_int_t ngx_http_mp4_read_stss_atom(ngx_http_mp4_file_t *mp4,
uint64_t atom_data_size);
static ngx_int_t ngx_http_mp4_update_stss_atom(ngx_http_mp4_file_t *mp4,
@ -343,6 +383,13 @@ static ngx_command_t ngx_http_mp4_commands[] = {
offsetof(ngx_http_mp4_conf_t, max_buffer_size),
NULL },
{ ngx_string("mp4_start_key_frame"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
NGX_HTTP_LOC_CONF_OFFSET,
offsetof(ngx_http_mp4_conf_t, start_key_frame),
NULL },
ngx_null_command
};
@ -829,6 +876,7 @@ ngx_http_mp4_process(ngx_http_mp4_file_t *mp4)
trak[i].size += trak[i].hdlr_size;
ngx_http_mp4_update_mdia_atom(mp4, &trak[i]);
trak[i].size += trak[i].tkhd_size;
ngx_http_mp4_update_edts_atom(mp4, &trak[i]);
ngx_http_mp4_update_trak_atom(mp4, &trak[i]);
mp4->moov_size += trak[i].size;
@ -1590,6 +1638,7 @@ ngx_http_mp4_read_tkhd_atom(ngx_http_mp4_file_t *mp4, uint64_t atom_data_size)
trak = ngx_mp4_last_trak(mp4);
trak->tkhd_size = atom_size;
trak->movie_duration = duration;
ngx_mp4_set_32value(tkhd_atom->size, atom_size);
@ -1985,6 +2034,59 @@ ngx_http_mp4_read_stbl_atom(ngx_http_mp4_file_t *mp4, uint64_t atom_data_size)
}
static void
ngx_http_mp4_update_edts_atom(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak)
{
ngx_buf_t *atom;
ngx_mp4_elst_atom_t *elst_atom;
ngx_mp4_edts_atom_t *edts_atom;
if (trak->prefix == 0) {
return;
}
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
"mp4 edts atom update prefix:%uL", trak->prefix);
edts_atom = &trak->edts_atom;
ngx_mp4_set_32value(edts_atom->size, sizeof(ngx_mp4_edts_atom_t)
+ sizeof(ngx_mp4_elst_atom_t));
ngx_mp4_set_atom_name(edts_atom, 'e', 'd', 't', 's');
atom = &trak->edts_atom_buf;
atom->temporary = 1;
atom->pos = (u_char *) edts_atom;
atom->last = (u_char *) edts_atom + sizeof(ngx_mp4_edts_atom_t);
trak->out[NGX_HTTP_MP4_EDTS_ATOM].buf = atom;
elst_atom = &trak->elst_atom;
ngx_mp4_set_32value(elst_atom->size, sizeof(ngx_mp4_elst_atom_t));
ngx_mp4_set_atom_name(elst_atom, 'e', 'l', 's', 't');
elst_atom->version[0] = 1;
elst_atom->flags[0] = 0;
elst_atom->flags[1] = 0;
elst_atom->flags[2] = 0;
ngx_mp4_set_32value(elst_atom->entries, 1);
ngx_mp4_set_64value(elst_atom->duration, trak->movie_duration);
ngx_mp4_set_64value(elst_atom->media_time, trak->prefix);
ngx_mp4_set_16value(elst_atom->media_rate, 1);
ngx_mp4_set_16value(elst_atom->reserved, 0);
atom = &trak->elst_atom_buf;
atom->temporary = 1;
atom->pos = (u_char *) elst_atom;
atom->last = (u_char *) elst_atom + sizeof(ngx_mp4_elst_atom_t);
trak->out[NGX_HTTP_MP4_ELST_ATOM].buf = atom;
trak->size += sizeof(ngx_mp4_edts_atom_t) + sizeof(ngx_mp4_elst_atom_t);
}
static void
ngx_http_mp4_update_stbl_atom(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak)
@ -2183,7 +2285,7 @@ static ngx_int_t
ngx_http_mp4_crop_stts_data(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak, ngx_uint_t start)
{
uint32_t count, duration, rest;
uint32_t count, duration, rest, key_prefix;
uint64_t start_time;
ngx_buf_t *data;
ngx_uint_t start_sample, entries, start_sec;
@ -2207,7 +2309,7 @@ ngx_http_mp4_crop_stts_data(ngx_http_mp4_file_t *mp4,
data = trak->out[NGX_HTTP_MP4_STTS_DATA].buf;
start_time = (uint64_t) start_sec * trak->timescale / 1000;
start_time = (uint64_t) start_sec * trak->timescale / 1000 + trak->prefix;
entries = trak->time_to_sample_entries;
start_sample = 0;
@ -2253,6 +2355,26 @@ ngx_http_mp4_crop_stts_data(ngx_http_mp4_file_t *mp4,
found:
if (start) {
key_prefix = ngx_http_mp4_seek_key_frame(mp4, trak, start_sample);
start_sample -= key_prefix;
while (rest < key_prefix) {
trak->prefix += rest * duration;
key_prefix -= rest;
entry--;
entries++;
count = ngx_mp4_get_32value(entry->count);
duration = ngx_mp4_get_32value(entry->duration);
rest = count;
}
trak->prefix += key_prefix * duration;
trak->duration += trak->prefix;
rest -= key_prefix;
ngx_mp4_set_32value(entry->count, count - rest);
data->pos = (u_char *) entry;
trak->time_to_sample_entries = entries;
@ -2277,6 +2399,49 @@ found:
}
static uint32_t
ngx_http_mp4_seek_key_frame(ngx_http_mp4_file_t *mp4, ngx_http_mp4_trak_t *trak,
uint32_t start_sample)
{
uint32_t key_prefix, sample, *entry, *end;
ngx_buf_t *data;
ngx_http_mp4_conf_t *conf;
conf = ngx_http_get_module_loc_conf(mp4->request, ngx_http_mp4_module);
if (!conf->start_key_frame) {
return 0;
}
data = trak->out[NGX_HTTP_MP4_STSS_DATA].buf;
if (data == NULL) {
return 0;
}
entry = (uint32_t *) data->pos;
end = (uint32_t *) data->last;
/* sync samples starts from 1 */
start_sample++;
key_prefix = 0;
while (entry < end) {
sample = ngx_mp4_get_32value(entry);
if (sample > start_sample) {
break;
}
key_prefix = start_sample - sample;
entry++;
}
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
"mp4 key frame prefix:%uD", key_prefix);
return key_prefix;
}
typedef struct {
u_char size[4];
u_char name[4];
@ -3614,6 +3779,7 @@ ngx_http_mp4_create_conf(ngx_conf_t *cf)
conf->buffer_size = NGX_CONF_UNSET_SIZE;
conf->max_buffer_size = NGX_CONF_UNSET_SIZE;
conf->start_key_frame = NGX_CONF_UNSET;
return conf;
}
@ -3628,6 +3794,7 @@ ngx_http_mp4_merge_conf(ngx_conf_t *cf, void *parent, void *child)
ngx_conf_merge_size_value(conf->buffer_size, prev->buffer_size, 512 * 1024);
ngx_conf_merge_size_value(conf->max_buffer_size, prev->max_buffer_size,
10 * 1024 * 1024);
ngx_conf_merge_value(conf->start_key_frame, prev->start_key_frame, 0);
return NGX_CONF_OK;
}