[patch]nginx mp4 module about "keyframe aligning"

gistfile1.c

Index: bundle/nginx-1.4.3/src/http/modules/ngx_http_mp4_module.c
===================================================================
--- bundle/nginx-1.4.3/src/http/modules/ngx_http_mp4_module.c	(revision 126116)
+++ bundle/nginx-1.4.3/src/http/modules/ngx_http_mp4_module.c	(working copy)
@@ -129,6 +129,7 @@
     off_t                 end;
     off_t                 content_length;
     ngx_uint_t            start;
+    ngx_uint_t            old_start;
     ngx_uint_t            length;
     uint32_t              timescale;
     ngx_http_request_t   *request;
@@ -2100,6 +2101,51 @@
 
 
 static ngx_int_t
+ngx_http_mp4_sync_sample_seek(ngx_http_mp4_file_t *mp4,ngx_http_mp4_trak_t *trak, ngx_uint_t *sample, ngx_uint_t old_sample, uint32_t duration, uint32_t timescale, ngx_uint_t flag)
+{
+    uint32_t     stss_sample, *stss_entry, *stss_end;
+    ngx_buf_t   *stss_data;
+    ngx_uint_t   stss_entries;
+
+    stss_data = trak->out[NGX_HTTP_MP4_STSS_DATA].buf;
+    if (stss_data == NULL)  return -1;
+
+    if ((mp4->start == 0) && (flag == 1)) {
+        return -1;
+    }
+
+    stss_entries = trak->sync_samples_entries;
+    stss_entry = (uint32_t *) stss_data->pos;
+    stss_end = (uint32_t *) stss_data->last;
+
+    while (stss_entry < stss_end) {
+        stss_sample = ngx_mp4_get_32value(stss_entry);
+
+        if (*sample < stss_sample) {
+           *sample = ngx_mp4_get_32value(stss_entry-1) - 1;
+           break;
+        }
+        if (*sample == stss_sample) {
+           *sample = ngx_mp4_get_32value(stss_entry) - 1;
+           break;
+        }
+
+        stss_entries--;
+        stss_entry++;
+    }
+    if (flag == 1) {
+        mp4->start = (*sample * duration) * 1000 / timescale;
+    }
+
+    if (flag == 0) {
+        mp4->length = (*sample - 1) * duration * 1000 / timescale  -  mp4->start;
+    }
+
+    return 0;
+}
+
+
+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)
 {
@@ -2106,19 +2152,19 @@
     uint32_t               count, duration, rest;
     uint64_t               start_time;
     ngx_buf_t             *data;
-    ngx_uint_t             start_sample, entries, start_sec;
+    ngx_uint_t             start_sample, entries, start_sec, old_start_sample;
     ngx_mp4_stts_entry_t  *entry, *end;
 
     if (start) {
         start_sec = mp4->start;
+        mp4->old_start = mp4->start;
 
         ngx_log_debug1(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                        "mp4 stts crop start_time:%ui", start_sec);
 
     } else if (mp4->length) {
-        start_sec = mp4->length;
-
-        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
+       start_sec = mp4->length + mp4->old_start;
+       ngx_log_debug1(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                        "mp4 stts crop end_time:%ui", start_sec);
 
     } else {
@@ -2134,6 +2180,7 @@
     entry = (ngx_mp4_stts_entry_t *) data->pos;
     end = (ngx_mp4_stts_entry_t *) data->last;
 
+
     while (entry < end) {
         count = ngx_mp4_get_32value(entry->count);
         duration = ngx_mp4_get_32value(entry->duration);
@@ -2144,6 +2191,10 @@
 
         if (start_time < (uint64_t) count * duration) {
             start_sample += (ngx_uint_t) (start_time / duration);
+            old_start_sample = start_sample; 
+            ngx_http_mp4_sync_sample_seek(mp4, trak, &start_sample, old_start_sample, duration, trak->timescale, start);
+            start_time = (uint64_t)start_sample * duration;
+
             rest = (uint32_t) (start_time / duration);
             goto found;
         }
@@ -2183,11 +2234,13 @@
                        trak->start_sample, count - rest);
 
     } else {
-        ngx_mp4_set_32value(entry->count, rest);
         data->last = (u_char *) (entry + 1);
         trak->time_to_sample_entries -= entries - 1;
-        trak->end_sample = trak->start_sample + start_sample;
 
+        trak->end_sample = start_sample - 1;
+
+        ngx_mp4_set_32value(entry->count, trak->end_sample - trak->start_sample);
+
         ngx_log_debug2(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                        "end_sample:%ui, new count:%uD",
                        trak->end_sample, rest);
@@ -2297,7 +2350,6 @@
 
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                    "sync sample entries:%uD", trak->sync_samples_entries);
-
     if (trak->sync_samples_entries) {
         entry = (uint32_t *) data->pos;
         end = (uint32_t *) data->last;
@@ -2305,8 +2357,10 @@
         start_sample = trak->start_sample;
 
         while (entry < end) {
+
             sample = ngx_mp4_get_32value(entry);
             sample -= start_sample;
+
             ngx_mp4_set_32value(entry, sample);
             entry++;
         }
@@ -2366,7 +2420,13 @@
         ngx_log_debug1(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                        "sync:%uD", sample);
 
-        if (sample >= start_sample) {
+        if (start) {
+            if (sample >= start_sample - 1) {
+               goto found;
+            }
+        }
+
+        if (sample >= start_sample - 1) {
             goto found;
         }