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[Patch] flv: add support for time offset

Jianyong Chen
August 11, 2019 05:50AM
Hi,

I have been reading nginx source code recently and found that flv module is too
simple, more specifically, it lacks support for time offset unlike mp4 module does.

However, in real life, the demand for time offset is more common than it for
byte offset, especially in CDN field. In addition to CDN, many video players use
time offset to implement drag function. But the original module only supports
byte offset, so I think it is necessary to add this feature and I have finished it.

To support time offset, I had to parse the metadata, but I haven’t found an
efficient and elegant solution, so I referred to the nginx-rtmp module in this
part(Thanks, Roman Arutyunyan). As for byte offset, I just kept it consistent
with the original module.

I published the project in GitHub, and here is the address:
https://github.com/BalusChen/nginx-flv-module, where you can find more detail.

By the way, does anyone have interest in aligning keyframes for mp4 module?
I'm willing to do this job.

And Maxim Dounin, could you please give me some comments or suggestions?
I'll appreciate it.


Here is the patch:

# HG changeset patch
# User Jianyong Chen <balus@foxmail.com>
# Date 1565510616 -28800
# Sun Aug 11 16:03:36 2019 +0800
# Node ID 739f513ab47fa70c8691cf38a22b27767dd2939b
# Parent fcd92ad76b7bb04b46c4b8fdfe14b6065acadf7d
HTTP: add support for time offset.

Add support for time offset to ngx_http_flv_module and keep consistent with the
original module while handling byte offset.

diff -r fcd92ad76b7b -r 739f513ab47f src/http/modules/ngx_http_flv_module.c
--- a/src/http/modules/ngx_http_flv_module.c Thu Aug 01 13:50:07 2019 +0300
+++ b/src/http/modules/ngx_http_flv_module.c Sun Aug 11 16:03:36 2019 +0800
@@ -1,6 +1,7 @@

/*
* Copyright (C) Igor Sysoev
+ * Copyright (C) Roman Arutyunyan
* Copyright (C) Nginx, Inc.
*/

@@ -8,8 +9,243 @@
#include <ngx_core.h>
#include <ngx_http.h>

+#define NGX_FLV_HEADER_SIGVER 0x464c5601
+
+#define NGX_FLV_HEADER_VIDEO 0x01
+#define NGX_FLV_HEADER_AUDIO 0x04
+
+#define NGX_FLV_TAG_TYPE_AUDIO 0x08
+#define NGX_FLV_TAG_TYPE_VIDEO 0x09
+#define NGX_FLV_TAG_TYPE_META 0x12
+#define NGX_FLV_TAG_TYPE_MASK 0x1f
+
+#define NGX_FLV_PACKET_AVC 0x07
+#define NGX_FLV_PACKET_AAC 0x0a
+
+#define NGX_FLV_AUDIO_CODECID_MASK 0xf0
+#define NGX_FLV_VIDEO_CODECID_MASK 0x0f
+#define NGX_FLV_VIDEO_FRAMETYPE_MASK 0xf0
+
+
+typedef struct {
+ u_char signature[3]; /* "FLV" */
+ u_char version[1]; /* 0x01 [version 1] */
+ u_char av_flags[1]; /* 0b00000 1[a] 0 1[v] */
+ u_char length[4]; /* 0x00000009 */
+ u_char tag_size[4]; /* 0x00000000 */
+} ngx_flv_header_t;
+
+
+typedef struct {
+ u_char type[1]; /* 0b00 0[filter] 00000[type] */
+ u_char size[3]; /* message length */
+ u_char timestamp[3]; /* pts in milliseconds */
+ u_char timestamp_ext[1]; /* upper 8 bits of timestamp */
+ u_char stream_id[3]; /* 0x000000 */
+
+ /* Audio: 0b0000[codec_id] 00[rate] 0[size] 0[type]
+ * Video: 0b0000[type] 0000[codec_id] */
+ u_char av_header[1];
+
+ /* Audio or Video: 0x00 is sequence_header */
+ u_char av_type[1];
+} ngx_flv_tag_header_t;
+
+
+#define NGX_FLV_HEADER_SIZE sizeof(ngx_flv_header_t)
+#define NGX_FLV_PREV_TAG_SIZE 4
+#define NGX_FLV_TAG_HEADER_SIZE 11
+#define NGX_FLV_HEADER_LENGTH (NGX_FLV_HEADER_SIZE - NGX_FLV_PREV_TAG_SIZE)
+
+#define ngx_flv_get_tag_size(p) \
+ ( ((uint32_t) ((u_char *) (p))[0] << 16) \
+ + ( ((u_char *) (p))[1] << 8) \
+ + ( ((u_char *) (p))[2]) )
+
+#define ngx_flv_get_timestamp(p) \
+ ( ((uint32_t) ((u_char *) (p))[3] << 24) \
+ + ( ((u_char *) (p))[0] << 16) \
+ + ( ((u_char *) (p))[1] << 8) \
+ + ( ((u_char *) (p))[2]) )
+
+#define ngx_flv_get_32value(p) \
+ ( ((uint32_t) ((u_char *) (p))[0] << 24) \
+ + ( ((u_char *) (p))[1] << 16) \
+ + ( ((u_char *) (p))[2] << 8) \
+ + ( ((u_char *) (p))[3]) )
+
+#define ngx_flv_get_64value(p) \
+ ( ((uint64_t) ((u_char *) (p))[0] << 56) \
+ + ((uint64_t) ((u_char *) (p))[1] << 48) \
+ + ((uint64_t) ((u_char *) (p))[2] << 40) \
+ + ((uint64_t) ((u_char *) (p))[3] << 32) \
+ + ((uint64_t) ((u_char *) (p))[4] << 24) \
+ + ( ((u_char *) (p))[5] << 16) \
+ + ( ((u_char *) (p))[6] << 8) \
+ + ( ((u_char *) (p))[7]) )
+
+#define ngx_flv_header_has_signature_version(p) \
+ (ngx_flv_get_32value(p) == NGX_FLV_HEADER_SIGVER)
+
+#define ngx_flv_header_has_audio(p) \
+ (((u_char *) (p))[0] & NGX_FLV_HEADER_AUDIO)
+
+#define ngx_flv_header_has_video(p) \
+ (((u_char *) (p))[0] & NGX_FLV_HEADER_VIDEO)
+
+#define ngx_flv_tag_type(p) \
+ (((u_char *) (p))[0] & NGX_FLV_TAG_TYPE_MASK)
+
+#define ngx_flv_tag_is_video(p) \
+ (ngx_flv_tag_type(p) == NGX_FLV_TAG_TYPE_VIDEO)
+
+#define ngx_flv_tag_is_audio(p) \
+ (ngx_flv_tag_type(p) == NGX_FLV_TAG_TYPE_AUDIO)
+
+#define ngx_flv_tag_is_meta(p) \
+ (ngx_flv_tag_type(p) == NGX_FLV_TAG_TYPE_META)
+
+#define ngx_flv_is_sequence_header(p) (((u_char *) (p))[0] == 0x00)
+
+#define ngx_flv_codec_is_avc(p) \
+ ((((u_char *) (p))[0] & NGX_FLV_VIDEO_CODECID_MASK) == NGX_FLV_PACKET_AVC)
+
+#define ngx_flv_video_frametype(p) \
+ ((((u_char *) (p))[0] & NGX_FLV_VIDEO_FRAMETYPE_MASK) >> 4)
+
+#define ngx_flv_video_is_keyframe(p) (ngx_flv_video_frametype(p) == 0x01)
+
+#define ngx_flv_codec_is_aac(p) \
+ (((((u_char *) (p))[0] & NGX_FLV_AUDIO_CODECID_MASK) >> 4) \
+ == NGX_FLV_PACKET_AAC)
+
+/* basic types */
+#define NGX_FLV_AMF_NUMBER 0x00
+#define NGX_FLV_AMF_BOOLEAN 0x01
+#define NGX_FLV_AMF_STRING 0x02
+#define NGX_FLV_AMF_OBJECT 0x03
+#define NGX_FLV_AMF_NULL 0x05
+#define NGX_FLV_AMF_ARRAY_NULL 0x06
+#define NGX_FLV_AMF_MIXED_ARRAY 0x08
+#define NGX_FLV_AMF_END 0x09
+#define NGX_FLV_AMF_ARRAY 0x0a
+
+/* extended types */
+#define NGX_FLV_AMF_INT8 0x0100
+#define NGX_FLV_AMF_INT16 0x0101
+#define NGX_FLV_AMF_INT32 0x0102
+#define NGX_FLV_AMF_VARIANT_ 0x0103
+
+/* r/w flags */
+#define NGX_FLV_AMF_OPTIONAL 0x1000
+#define NGX_FLV_AMF_TYPELESS 0x2000
+#define NGX_FLV_AMF_CONTEXT 0x4000
+
+
+static ngx_inline double
+ngx_flv_get_amf_number(u_char *p)
+{
+ union {
+ uint64_t i;
+ double f;
+ } uint2double;
+
+ uint2double.i = ngx_flv_get_64value(p);
+
+ return uint2double.f;
+}
+
+
+typedef struct {
+ ngx_int_t type;
+ ngx_str_t name;
+ void *data;
+ size_t len;
+} ngx_flv_amf_elt_t;
+
+
+typedef struct {
+ size_t buffer_size;
+ size_t max_buffer_size;
+ ngx_flag_t time_offset;
+ ngx_flag_t with_metadata;
+} ngx_http_flv_conf_t;
+
+
+typedef struct {
+ ngx_file_t file;
+ ngx_http_request_t *request;
+
+ u_char *buffer;
+ u_char *buffer_start;
+ u_char *buffer_pos;
+ u_char *buffer_end;
+ size_t buffer_size;
+
+ off_t offset;
+ off_t file_end;
+ off_t sequence_end;
+ off_t necessary_len;
+ off_t start_offset;
+ off_t end_offset;
+ ngx_uint_t start;
+ ngx_uint_t end;
+
+ unsigned has_audio:1;
+ unsigned has_video:1;
+ unsigned met_audio:1;
+ unsigned met_video:1;
+ unsigned aac_audio:1;
+ unsigned avc_video:1;
+ unsigned with_metadata:1;
+
+ ngx_chain_t *necessary;
+ ngx_chain_t metadata;
+ ngx_chain_t audio_sequence_header;
+ ngx_chain_t video_sequence_header;
+
+ ngx_buf_t metadata_buf;
+ ngx_buf_t audio_sequence_buf;
+ ngx_buf_t video_sequence_buf;
+
+ u_char *filepositions;
+ u_char *times;
+ uint32_t filepositions_nelts;
+ uint32_t times_nelts;
+} ngx_http_flv_file_t;
+
+
+#define ngx_http_flv_tag_next(flv, n) \
+ flv->buffer_pos += (size_t) n; \
+ flv->offset += n
+
+
+static ngx_int_t ngx_http_flv_handler(ngx_http_request_t *r);
+static ngx_int_t ngx_http_flv_atofp(u_char *line, size_t n, size_t point);
+
+static ngx_int_t ngx_http_flv_process(ngx_http_flv_file_t *flv);
+static ngx_int_t ngx_http_flv_read(ngx_http_flv_file_t *flv, size_t size);
+static ngx_int_t ngx_http_flv_read_header(ngx_http_flv_file_t *flv);
+static ngx_int_t ngx_http_flv_read_metadata(ngx_http_flv_file_t *flv);
+static ngx_int_t ngx_http_flv_read_tags(ngx_http_flv_file_t *flv);
+static ngx_int_t ngx_http_flv_parse_metadata(ngx_http_flv_file_t *flv);
+static off_t ngx_http_flv_timestamp_to_offset(ngx_http_flv_file_t *flv,
+ ngx_uint_t timestamp, ngx_uint_t start);
+
+static void *ngx_flv_amf_reverse_copy(void *dst, void *src, size_t len);
+static ngx_int_t ngx_flv_amf_is_compatible_type(uint8_t t1, uint8_t t2);
+static ngx_int_t ngx_flv_amf_get(ngx_http_flv_file_t *flv, void *p, size_t n);
+static ngx_int_t ngx_flv_amf_read(ngx_http_flv_file_t *flv,
+ ngx_flv_amf_elt_t *elts, size_t nelts);
+static ngx_int_t ngx_flv_amf_read_object(ngx_http_flv_file_t *flv,
+ ngx_flv_amf_elt_t *elts, size_t nelts);
+static ngx_int_t ngx_flv_amf_read_array(ngx_http_flv_file_t *flv,
+ ngx_flv_amf_elt_t *elts, size_t nelts);

static char *ngx_http_flv(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
+static void *ngx_http_flv_create_conf(ngx_conf_t *cf);
+static char *ngx_http_flv_merge_conf(ngx_conf_t *cf, void *parent, void *child);
+

static ngx_command_t ngx_http_flv_commands[] = {

@@ -20,13 +256,38 @@
0,
NULL },

+ { ngx_string("flv_time_offset"),
+ 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_flv_conf_t, time_offset),
+ NULL },
+
+ { ngx_string("flv_with_metadata"),
+ 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_flv_conf_t, with_metadata),
+ NULL },
+
+ { ngx_string("flv_buffer_size"),
+ NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+ ngx_conf_set_size_slot,
+ NGX_HTTP_LOC_CONF_OFFSET,
+ offsetof(ngx_http_flv_conf_t, buffer_size),
+ NULL },
+
+ { ngx_string("flv_max_buffer_size"),
+ NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+ ngx_conf_set_size_slot,
+ NGX_HTTP_LOC_CONF_OFFSET,
+ offsetof(ngx_http_flv_conf_t, max_buffer_size),
+ NULL },
+
ngx_null_command
};


-static u_char ngx_flv_header[] = "FLV\x1\x5\0\0\0\x9\0\0\0\0";
-
-
static ngx_http_module_t ngx_http_flv_module_ctx = {
NULL, /* preconfiguration */
NULL, /* postconfiguration */
@@ -37,8 +298,8 @@
NULL, /* create server configuration */
NULL, /* merge server configuration */

- NULL, /* create location configuration */
- NULL /* merge location configuration */
+ ngx_http_flv_create_conf, /* create location configuration */
+ ngx_http_flv_merge_conf /* merge location configuration */
};


@@ -58,18 +319,23 @@
};


+static u_char ngx_flv_header[] = "FLV\x1\x5\0\0\0\x9\0\0\0\0";
+
+
static ngx_int_t
ngx_http_flv_handler(ngx_http_request_t *r)
{
+ off_t start, end, len;
u_char *last;
- off_t start, len;
size_t root;
- ngx_int_t rc;
- ngx_uint_t level, i;
ngx_str_t path, value;
ngx_log_t *log;
ngx_buf_t *b;
+ ngx_int_t rc, time_start, time_end;
+ ngx_uint_t level, i, time_offset;
ngx_chain_t out[2];
+ ngx_http_flv_file_t *flv;
+ ngx_http_flv_conf_t *conf;
ngx_open_file_info_t of;
ngx_http_core_loc_conf_t *clcf;

@@ -167,24 +433,114 @@

r->root_tested = !r->error_page;

+ conf = ngx_http_get_module_loc_conf(r, ngx_http_flv_module);
+ time_offset = (ngx_uint_t) conf->time_offset;
+ time_start = -1;
+ time_end = 0;
start = 0;
+ end = of.size;
len = of.size;
i = 1;
+ flv = NULL;

if (r->args.len) {

+ if (ngx_http_arg(r, (u_char *) "time_offset", 11, &value) == NGX_OK) {
+ time_offset = 1;
+ }
+
if (ngx_http_arg(r, (u_char *) "start", 5, &value) == NGX_OK) {

- start = ngx_atoof(value.data, value.len);
+ if (time_offset) {
+ time_start = ngx_http_flv_atofp(value.data, value.len, 3);
+
+ } else {
+ start = ngx_atoof(value.data, value.len);
+
+ if (start == NGX_ERROR || start >= len) {
+ start = 0;
+ }
+
+ if (start) {
+ len = sizeof(ngx_flv_header) - 1 + len - start;
+ i = 0;
+ }
+ }
+ }
+
+ /*
+ * To keep consistent with the original module,
+ * we just skip the 'end' argument while handling byte offset.
+ */
+
+ if (time_offset
+ && ngx_http_arg(r, (u_char *) "end", 3, &value) == NGX_OK)
+ {
+ time_end = ngx_http_flv_atofp(value.data, value.len, 3);

- if (start == NGX_ERROR || start >= len) {
- start = 0;
+ if (time_end >= 0 && time_start < 0) {
+ time_start = 0;
+ }
+ }
+ }
+
+ if (time_start >= 0) {
+ ngx_log_debug2(NGX_LOG_DEBUG_HTTP, log, 0,
+ "http flv time_offset time_start=%i time_end=%i",
+ time_start, time_end);
+
+ if (time_end < time_start) {
+
+ /* denotes the file end */
+
+ time_end = NGX_MAX_INT_T_VALUE;
+ }
+
+ flv = ngx_pcalloc(r->pool, sizeof(ngx_http_flv_file_t));
+ if (flv == NULL) {
+ return NGX_HTTP_INTERNAL_SERVER_ERROR;
+ }
+ flv->file.fd = of.fd;
+ flv->file.name = path;
+ flv->file.log = r->connection->log;
+ flv->file_end = of.size;
+ flv->buffer_size = conf->buffer_size;
+ flv->with_metadata = conf->with_metadata;
+ flv->start = time_start;
+ flv->end = time_end;
+ flv->request = r;
+
+ switch (ngx_http_flv_process(flv)) {
+
+ case NGX_DECLINED:
+ if (flv->buffer) {
+ ngx_pfree(r->pool, flv->buffer);
}

- if (start) {
- len = sizeof(ngx_flv_header) - 1 + len - start;
+ ngx_pfree(r->pool, flv);
+ flv = NULL;
+
+ break;
+
+ case NGX_OK:
+ start = flv->start_offset;
+ end = flv->end_offset;
+ len = end - start;
+ if (start > 0) {
+ len += sizeof(ngx_flv_header) - 1 + flv->necessary_len;
i = 0;
}
+
+ break;
+
+ default: /* NGX_ERROR */
+ if (flv->buffer) {
+ ngx_pfree(r->pool, flv->buffer);
+ }
+
+ ngx_pfree(r->pool, flv);
+
+ return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
}

@@ -214,6 +570,14 @@

out[0].buf = b;
out[0].next = &out[1];
+
+ if (flv && flv->necessary) {
+ out[0].next = flv->necessary;
+ while (flv->necessary->next) {
+ flv->necessary= flv->necessary->next;
+ }
+ flv->necessary->next = &out[1];
+ }
}


@@ -236,7 +600,7 @@
}

b->file_pos = start;
- b->file_last = of.size;
+ b->file_last = end;

b->in_file = b->file_last ? 1: 0;
b->last_buf = (r == r->main) ? 1 : 0;
@@ -254,6 +618,739 @@
}


+static ngx_int_t
+ngx_http_flv_atofp(u_char *line, size_t n, size_t point)
+{
+ ngx_int_t value, cutoff, cutlim;
+ ngx_uint_t dot;
+
+ if (n == 0) {
+ return NGX_ERROR;
+ }
+
+ cutoff = NGX_MAX_INT_T_VALUE / 10;
+ cutlim = NGX_MAX_INT_T_VALUE % 10;
+
+ dot = 0;
+
+ for (value = 0; n--; line++) {
+
+ if (*line == '.') {
+ if (dot) {
+ return NGX_ERROR;
+ }
+
+ dot = 1;
+ continue;
+ }
+
+ if (*line < '0' || *line > '9') {
+ return NGX_ERROR;
+ }
+
+ if (dot && point == 0) {
+ continue;
+ }
+
+ if (value >= cutoff && (value > cutoff || *line - '0' > cutlim)) {
+ return NGX_ERROR;
+ }
+
+ value = value * 10 + (*line - '0');
+ point -= dot;
+ }
+
+ while (point--) {
+ if (value > cutoff) {
+ return NGX_ERROR;
+ }
+
+ value = value * 10;
+ }
+
+ return value;
+}
+
+
+static ngx_int_t
+ngx_http_flv_process(ngx_http_flv_file_t *flv)
+{
+ ngx_int_t rc;
+ ngx_chain_t **prev;
+
+ ngx_log_debug2(NGX_LOG_DEBUG_HTTP, flv->file.log, 0,
+ "flv start:%ui, end:%ui", flv->start, flv->end);
+
+ rc = ngx_http_flv_read_header(flv);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ rc = ngx_http_flv_read_metadata(flv);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ rc = ngx_http_flv_read_tags(flv);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ rc = ngx_http_flv_parse_metadata(flv);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ flv->start_offset = ngx_http_flv_timestamp_to_offset(flv, flv->start, 1);
+ flv->end_offset = ngx_http_flv_timestamp_to_offset(flv, flv->end, 0);
+
+ ngx_log_debug2(NGX_LOG_DEBUG_HTTP, flv->file.log, 0,
+ "flv start_offset:%O end_offset:%O",
+ flv->start_offset, flv->end_offset);
+
+ if (flv->end_offset <= flv->start_offset) {
+ return NGX_DECLINED;
+ }
+
+ prev = &flv->necessary;
+
+ if (flv->with_metadata && flv->metadata.buf) {
+ *prev = &flv->metadata;
+ prev = &flv->metadata.next;
+ flv->necessary_len += ngx_buf_size(flv->metadata.buf);
+ }
+
+ if (flv->audio_sequence_header.buf) {
+ *prev = &flv->audio_sequence_header;
+ prev = &flv->audio_sequence_header.next;
+ flv->necessary_len += ngx_buf_size(flv->audio_sequence_header.buf);
+ }
+
+ if (flv->video_sequence_header.buf) {
+ *prev = &flv->video_sequence_header;
+ flv->necessary_len += ngx_buf_size(flv->video_sequence_header.buf);
+ }
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_flv_read(ngx_http_flv_file_t *flv, size_t size)
+{
+ ssize_t n;
+
+ if (flv->buffer_pos + size <= flv->buffer_end) {
+ return NGX_OK;
+ }
+
+ if (flv->offset + (off_t) flv->buffer_size > flv->file_end) {
+ flv->buffer_size = (size_t) (flv->file_end - flv->offset);
+ }
+
+ if (flv->buffer_size < size) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "\"%s\" flv file truncated", flv->file.name.data);
+ return NGX_ERROR;
+ }
+
+ if (flv->buffer == NULL) {
+ flv->buffer = ngx_palloc(flv->request->pool, flv->buffer_size);
+ if (flv->buffer == NULL) {
+ return NGX_ERROR;
+ }
+
+ flv->buffer_start = flv->buffer;
+ }
+
+ n = ngx_read_file(&flv->file, flv->buffer_start, flv->buffer_size,
+ flv->offset);
+
+ if (n == NGX_ERROR) {
+ return NGX_ERROR;
+ }
+
+ if ((size_t) n != flv->buffer_size) {
+ ngx_log_error(NGX_LOG_CRIT, flv->file.log, 0,
+ ngx_read_file_n " read only %z of %z from \"%s\"",
+ n, flv->buffer_size, flv->file.name.data);
+ return NGX_ERROR;
+ }
+
+ flv->buffer_pos = flv->buffer_start;
+ flv->buffer_end = flv->buffer_start + flv->buffer_size;
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_flv_read_header(ngx_http_flv_file_t *flv)
+{
+ ngx_flv_header_t *hdr;
+
+ ngx_log_debug0(NGX_LOG_DEBUG_HTTP, flv->file.log, 0, "flv header");
+
+ if (ngx_http_flv_read(flv, NGX_FLV_HEADER_SIZE) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ if (!ngx_flv_header_has_signature_version(flv->buffer_pos)) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv wrong signature or version");
+ return NGX_ERROR;
+ }
+
+ hdr = (ngx_flv_header_t *) flv->buffer_pos;
+
+ if (ngx_flv_get_32value(hdr->length) != NGX_FLV_HEADER_LENGTH) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv wrong header length");
+ return NGX_ERROR;
+ }
+
+ if (ngx_flv_get_32value(hdr->tag_size) != 0) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv wrong header prev_tag size");
+ return NGX_ERROR;
+ }
+
+ flv->has_video = ngx_flv_header_has_video(hdr->av_flags);
+ flv->has_audio = ngx_flv_header_has_audio(hdr->av_flags);
+
+ ngx_http_flv_tag_next(flv, NGX_FLV_HEADER_SIZE);
+
+ return NGX_OK;
+}
+
+
+/*
+ * Small excess buffer to process tags after metadata.
+ */
+#define NGX_HTTP_FLV_META_BUFFER_EXCESS (16 * 1024)
+
+static ngx_int_t
+ngx_http_flv_read_metadata(ngx_http_flv_file_t *flv)
+{
+ uint32_t size;
+ ngx_buf_t *buf;
+ ngx_http_flv_conf_t *conf;
+ ngx_flv_tag_header_t *tag;
+
+ ngx_log_debug0(NGX_LOG_DEBUG_HTTP, flv->file.log, 0, "flv metadata tag");
+
+ if (ngx_http_flv_read(flv, NGX_FLV_HEADER_SIZE) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ tag = (ngx_flv_tag_header_t *) flv->buffer_pos;
+ size = NGX_FLV_TAG_HEADER_SIZE + ngx_flv_get_tag_size(tag->size)
+ + NGX_FLV_PREV_TAG_SIZE;
+
+ if (!ngx_flv_tag_is_meta(tag->type)) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv first tag is not metadata");
+ return NGX_DECLINED;
+ }
+
+ if (size + NGX_HTTP_FLV_META_BUFFER_EXCESS > flv->buffer_size) {
+ conf = ngx_http_get_module_loc_conf(flv->request, ngx_http_flv_module);
+
+ if (size > conf->max_buffer_size) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "\"%s\" flv metadata tag is too large:%D, "
+ "you may want to increase flv_max_buffer_size",
+ flv->file.name.data, size);
+ return NGX_ERROR;
+ }
+
+ ngx_pfree(flv->request->pool, flv->buffer);
+ flv->buffer = NULL;
+ flv->buffer_pos = NULL;
+ flv->buffer_end = NULL;
+
+ flv->buffer_size = (size_t) size + NGX_HTTP_FLV_META_BUFFER_EXCESS;
+ }
+
+ if (ngx_http_flv_read(flv, (size_t) size) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, flv->file.log, 0,
+ "flv metadata_len:%D", size);
+
+ buf = &flv->metadata_buf;
+ buf->temporary = 1;
+ buf->pos = flv->buffer_pos;
+ buf->last = flv->buffer_pos + size;
+ buf->start = buf->pos;
+ buf->end = buf->last;
+
+ flv->metadata.buf = buf;
+
+ ngx_http_flv_tag_next(flv, size);
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_flv_read_tags(ngx_http_flv_file_t *flv)
+{
+ uint32_t size;
+ ngx_buf_t *buf;
+ ngx_flv_tag_header_t *tag;
+
+ ngx_log_debug0(NGX_LOG_DEBUG_HTTP, flv->file.log, 0, "flv av tag");
+
+ while (flv->buffer_pos + NGX_FLV_HEADER_SIZE < flv->buffer_end) {
+
+ if (ngx_http_flv_read(flv, NGX_FLV_HEADER_SIZE) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ tag = (ngx_flv_tag_header_t *) flv->buffer_pos;
+ size = NGX_FLV_TAG_HEADER_SIZE + ngx_flv_get_tag_size(tag->size)
+ + NGX_FLV_PREV_TAG_SIZE;
+
+ if (flv->buffer_pos + size > flv->buffer_end) {
+ break;
+ }
+
+ switch ngx_flv_tag_type(tag->type) {
+
+ case NGX_FLV_TAG_TYPE_AUDIO:
+ if (flv->met_audio) {
+ break;
+ }
+ flv->met_audio = 1;
+ flv->aac_audio = ngx_flv_codec_is_aac(tag->av_header);
+ if (!flv->aac_audio) {
+ break;
+ }
+ if (!ngx_flv_is_sequence_header(tag->av_type)) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv first audio tag is not sequence header");
+ return NGX_ERROR;
+ }
+ flv->sequence_end = flv->offset + size;
+
+ buf = &flv->audio_sequence_buf;
+ buf->temporary = 1;
+ buf->pos = flv->buffer_pos;
+ buf->last = flv->buffer_pos + size;
+
+ flv->audio_sequence_header.buf = buf;
+ break;
+
+ case NGX_FLV_TAG_TYPE_VIDEO:
+ if (flv->met_video) {
+ break;
+ }
+ flv->met_video = 1;
+ flv->avc_video = ngx_flv_codec_is_avc(tag->av_header);
+ if (!flv->avc_video) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv does not support time offset, avc required");
+ return NGX_DECLINED;
+ }
+ if (!ngx_flv_is_sequence_header(tag->av_type)) {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv first video tag is not sequence header");
+ return NGX_ERROR;
+ }
+ flv->sequence_end = flv->offset + size;
+
+ buf = &flv->video_sequence_buf;
+ buf->temporary = 1;
+ buf->pos = flv->buffer_pos;
+ buf->last = flv->buffer_pos + size;
+
+ flv->video_sequence_header.buf = buf;
+ break;
+
+ default:
+ break;
+ }
+
+ if (flv->met_audio && flv->met_video) {
+ return NGX_OK;
+ }
+
+ ngx_http_flv_tag_next(flv, size);
+ }
+
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv no a/v tag found within %DB after metadata",
+ NGX_HTTP_FLV_META_BUFFER_EXCESS);
+
+ return NGX_DECLINED;
+}
+
+
+static ngx_int_t
+ngx_http_flv_parse_metadata(ngx_http_flv_file_t *flv)
+{
+ static u_char *filepositions_pos;
+ static u_char *times_pos;
+
+ static ngx_flv_amf_elt_t in_keyframes[] = {
+
+ { NGX_FLV_AMF_ARRAY | NGX_FLV_AMF_CONTEXT,
+ ngx_string("filepositions"),
+ &filepositions_pos, 0 },
+
+ { NGX_FLV_AMF_ARRAY | NGX_FLV_AMF_CONTEXT,
+ ngx_string("times"),
+ &times_pos, 0 }
+ };
+
+ static ngx_flv_amf_elt_t in_inf[] = {
+
+ { NGX_FLV_AMF_OBJECT,
+ ngx_string("keyframes"),
+ in_keyframes, sizeof(in_keyframes) },
+ };
+
+ static ngx_flv_amf_elt_t in_elts[] = {
+
+ { NGX_FLV_AMF_STRING,
+ ngx_null_string,
+ NULL, 0 },
+
+ { NGX_FLV_AMF_OBJECT,
+ ngx_null_string,
+ in_inf, sizeof(in_inf) }
+ };
+
+ times_pos = NULL;
+ filepositions_pos = NULL;
+ flv->metadata.buf->pos += NGX_FLV_TAG_HEADER_SIZE;
+
+ if (ngx_flv_amf_read(flv, in_elts, sizeof(in_elts) / sizeof(in_elts[0]))
+ != NGX_OK)
+ {
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv metadata has no necessary element like keyframes");
+ return NGX_DECLINED;
+ }
+
+ if (times_pos != NULL) {
+ flv->times_nelts = ngx_flv_get_32value(times_pos);
+ flv->times = times_pos + 4;
+ }
+
+ if (filepositions_pos != NULL) {
+ flv->filepositions_nelts = ngx_flv_get_32value(filepositions_pos);
+ flv->filepositions = filepositions_pos + 4;
+ }
+
+ ngx_log_debug2(NGX_LOG_DEBUG_HTTP, flv->file.log, 0, "flv keyframes,"
+ " times_nelts:%D filepositions_nelts:%D",
+ flv->times_nelts, flv->filepositions_nelts);
+
+ if (!flv->times_nelts || flv->times_nelts != flv->filepositions_nelts) {
+ return NGX_DECLINED;
+ }
+
+ flv->metadata.buf->pos = flv->metadata.buf->start;
+
+ return NGX_OK;
+}
+
+
+static off_t
+ngx_http_flv_timestamp_to_offset(ngx_http_flv_file_t *flv, ngx_uint_t timestamp,
+ ngx_uint_t start)
+{
+ off_t offset;
+ u_char *times, *filepositions;
+ ngx_int_t left, right, middle;
+ ngx_uint_t rv, first, last;
+
+ times = flv->times;
+ right = flv->times_nelts - 1;
+ left = 0;
+
+ first = (ngx_uint_t) (1000 * ngx_flv_get_amf_number(&times[left*9 + 1]));
+ last = (ngx_uint_t) (1000 * ngx_flv_get_amf_number(&times[right*9 + 1]));
+
+ if (timestamp <= first || timestamp >= last) {
+
+ if (start) {
+ return 0;
+
+ } else {
+ return flv->file_end;
+ }
+ }
+
+ rv = 0;
+ middle = 0;
+
+ while (left <= right) {
+ middle = (left + right) / 2;
+
+ rv = (ngx_uint_t) (1000 * ngx_flv_get_amf_number(&times[middle*9 + 1]));
+
+ if (rv > timestamp) {
+ right = middle - 1;
+
+ } else if (rv < timestamp) {
+ left = middle + 1;
+
+ } else {
+ break;
+ }
+ }
+
+ if (middle > 0 && timestamp < rv) {
+ middle--;
+ }
+
+ filepositions = flv->filepositions;
+ offset = (off_t) ngx_flv_get_amf_number(&filepositions[middle*9 + 1]);
+
+ if (start && offset <= flv->sequence_end) {
+ return 0;
+ }
+
+ return offset;
+}
+
+
+static ngx_inline void *
+ngx_flv_amf_reverse_copy(void *dst, void *src, size_t len)
+{
+ size_t k;
+
+ if (dst == NULL || src == NULL) {
+ return NULL;
+ }
+
+ for (k = 0; k < len; ++k) {
+ ((u_char*)dst)[k] = ((u_char*)src)[len - 1 - k];
+ }
+
+ return dst;
+}
+
+
+static ngx_int_t
+ngx_flv_amf_is_compatible_type(uint8_t t1, uint8_t t2)
+{
+ return t1 == t2
+ || (t1 == NGX_FLV_AMF_OBJECT && t2 == NGX_FLV_AMF_MIXED_ARRAY)
+ || (t2 == NGX_FLV_AMF_OBJECT && t1 == NGX_FLV_AMF_MIXED_ARRAY);
+}
+
+
+static ngx_int_t
+ngx_flv_amf_get(ngx_http_flv_file_t *flv, void *p, size_t n)
+{
+ u_char *data;
+
+ if (flv->metadata.buf->pos + n > flv->metadata.buf->last) {
+ return NGX_ERROR;
+ }
+
+ data = flv->metadata.buf->pos;
+ if (p != NULL) {
+ ngx_cpymem(p, data, n);
+ }
+ flv->metadata.buf->pos += n;
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_flv_amf_read(ngx_http_flv_file_t *flv, ngx_flv_amf_elt_t *elts,
+ size_t nelts)
+{
+ void *data;
+ u_char buf[8];
+ size_t n;
+ uint8_t type8;
+ uint16_t len;
+ uint32_t max_index;
+ ngx_uint_t type;
+
+ for (n = 0; n < nelts; n++) {
+
+ if (ngx_flv_amf_get(flv, &type8, 1) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ type = type8;
+ data = (elts &&
+ ngx_flv_amf_is_compatible_type((uint8_t) (elts->type & 0xFF),
+ (uint8_t) type))
+ ? elts->data
+ : NULL;
+
+ if (elts && (elts->type & NGX_FLV_AMF_CONTEXT)) {
+ if (data) {
+ * ((u_char **) data) = flv->metadata.buf->pos;
+ }
+ data = NULL;
+ }
+
+ switch (type) {
+
+ case NGX_FLV_AMF_NUMBER:
+ if (ngx_flv_amf_get(flv, buf, 8) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ ngx_flv_amf_reverse_copy(data, buf, 8);
+
+ break;
+
+ case NGX_FLV_AMF_BOOLEAN:
+ if (ngx_flv_amf_get(flv, data, 1) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ break;
+
+ case NGX_FLV_AMF_STRING:
+ if (ngx_flv_amf_get(flv, buf, 2) != NGX_OK) {
+ return NGX_ERROR;
+ }
+ ngx_flv_amf_reverse_copy(&len, buf, 2);
+
+ if (ngx_flv_amf_get(flv, data, len) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ break;
+
+ case NGX_FLV_AMF_MIXED_ARRAY:
+ if (ngx_flv_amf_get(flv, &max_index, 4) != NGX_OK) {
+ return NGX_ERROR;
+ }
+ /* fall through */
+
+ case NGX_FLV_AMF_OBJECT:
+ if (ngx_flv_amf_read_object(flv, data,
+ data && elts ? elts->len / sizeof(elts[0]) : 0
+ ) != NGX_OK)
+ {
+ return NGX_ERROR;
+ }
+
+ break;
+
+ case NGX_FLV_AMF_ARRAY:
+ if (ngx_flv_amf_read_array(flv, data,
+ data && elts ? elts->len / sizeof(elts[0]) : 0
+ ) != NGX_OK)
+ {
+ return NGX_ERROR;
+ }
+
+ break;
+
+ default:
+ ngx_log_error(NGX_LOG_ERR, flv->file.log, 0,
+ "flv unknown amf type %d in \"%s\"",
+ type, flv->file.name.data);
+ return NGX_ERROR;
+ }
+
+ if (elts) {
+ elts++;
+ }
+ }
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_flv_amf_read_object(ngx_http_flv_file_t *flv, ngx_flv_amf_elt_t *elts,
+ size_t nelts)
+{
+ u_char buf[2];
+ size_t n, namelen, maxlen;
+ uint8_t type;
+ uint16_t len;
+
+ maxlen = 0;
+ for (n = 0; n < nelts; ++n) {
+ namelen = elts[n].name.len;
+ if (namelen > maxlen) {
+ maxlen = namelen;
+ }
+ }
+
+ for ( ;; ) {
+
+#if !(NGX_WIN32)
+ char name[maxlen];
+#else
+ char name[1024];
+ if (maxlen > sizeof(name)) {
+ return NGX_ERROR;
+ }
+#endif
+
+ if (ngx_flv_amf_get(flv, buf, 2) != NGX_OK) {
+ return NGX_ERROR;
+ }
+ ngx_flv_amf_reverse_copy(&len, buf, 2);
+
+ if (len == 0) {
+ break;
+ }
+
+ if (ngx_flv_amf_get(flv, name, len) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ for (n = 0; n < nelts
+ && (len != elts[n].name.len
+ || ngx_strncmp(name, elts[n].name.data, len) != 0);
+ ++n);
+
+ if (ngx_flv_amf_read(flv, n < nelts ? &elts[n] : NULL, 1) != NGX_OK) {
+ return NGX_ERROR;
+ }
+ }
+
+ if (ngx_flv_amf_get(flv, &type, 1) != NGX_OK || type != NGX_FLV_AMF_END) {
+ return NGX_ERROR;
+ }
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_flv_amf_read_array(ngx_http_flv_file_t *flv, ngx_flv_amf_elt_t *elts,
+ size_t nelts)
+{
+ u_char buf[4];
+ size_t n;
+ uint32_t len;
+
+ if (ngx_flv_amf_get(flv, buf, 4) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ ngx_flv_amf_reverse_copy(&len, buf, 4);
+
+ for (n = 0; n < len; ++n) {
+ if (ngx_flv_amf_read(flv, n < nelts ? &elts[n] : NULL, 1) != NGX_OK) {
+ return NGX_ERROR;
+ }
+ }
+
+ return NGX_OK;
+}
+
+
static char *
ngx_http_flv(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
@@ -264,3 +1361,38 @@

return NGX_CONF_OK;
}
+
+
+static void *
+ngx_http_flv_create_conf(ngx_conf_t *cf)
+{
+ ngx_http_flv_conf_t *conf;
+
+ conf = ngx_palloc(cf->pool, sizeof(ngx_http_flv_conf_t));
+ if (conf == NULL) {
+ return NULL;
+ }
+
+ conf->buffer_size = NGX_CONF_UNSET_SIZE;
+ conf->max_buffer_size = NGX_CONF_UNSET_SIZE;
+ conf->time_offset = NGX_CONF_UNSET;
+ conf->with_metadata = NGX_CONF_UNSET;
+
+ return conf;
+}
+
+
+static char *
+ngx_http_flv_merge_conf(ngx_conf_t *cf, void *parent, void *child)
+{
+ ngx_http_flv_conf_t *prev = parent;
+ ngx_http_flv_conf_t *conf = 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,
+ 2 * 1024 * 1024);
+ ngx_conf_merge_value(conf->time_offset, prev->time_offset, 0);
+ ngx_conf_merge_value(conf->with_metadata, prev->with_metadata, 0);
+
+ return NGX_CONF_OK;
+}
_______________________________________________
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Subject Author Views Posted

[Patch] flv: add support for time offset

Jianyong Chen 46 August 11, 2019 05:50AM

Re:[Patch] flv: add support for time offset

winshining 8 August 12, 2019 07:08AM

Re: [Patch] flv: add support for time offset

Jianyong Chen 12 August 12, 2019 10:02AM

Re: [Patch] flv: add support for time offset

Maxim Dounin 11 August 12, 2019 07:34AM

Re: [Patch] flv: add support for time offset

Jianyong Chen 18 August 12, 2019 11:12PM



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