From c4f8c453ae2f735fc2320856e15e66510d74fd72 Mon Sep 17 00:00:00 2001
From: Antti Ajanki <antti.ajanki@iki.fi>
Date: Sun, 22 Feb 2015 21:03:49 +0200
Subject: [PATCH] [f4m] Refresh fragment list periodically on live streams

---
 youtube_dl/downloader/f4m.py | 59 ++++++++++++++++++++++++++++++------
 1 file changed, 49 insertions(+), 10 deletions(-)

diff --git a/youtube_dl/downloader/f4m.py b/youtube_dl/downloader/f4m.py
index 7b8fe8cf57..1df9ebe5b2 100644
--- a/youtube_dl/downloader/f4m.py
+++ b/youtube_dl/downloader/f4m.py
@@ -121,7 +121,8 @@ class FlvReader(io.BytesIO):
 
         self.read_unsigned_int()  # BootstrapinfoVersion
         # Profile,Live,Update,Reserved
-        self.read(1)
+        flags = self.read_unsigned_char()
+        live = flags & 0x20 != 0
         # time scale
         self.read_unsigned_int()
         # CurrentMediaTime
@@ -160,6 +161,7 @@ class FlvReader(io.BytesIO):
         return {
             'segments': segments,
             'fragments': fragments,
+            'live': live,
         }
 
     def read_bootstrap_info(self):
@@ -182,6 +184,10 @@ def build_fragments_list(boot_info):
     for segment, fragments_count in segment_run_table['segment_run']:
         for _ in range(fragments_count):
             res.append((segment, next(fragments_counter)))
+
+    if boot_info['live']:
+        res = res[-2:]
+
     return res
 
 
@@ -246,6 +252,38 @@ class F4mFD(FileDownloader):
             self.report_error('Unsupported DRM')
         return media
 
+    def _get_bootstrap_from_url(self, bootstrap_url):
+        bootstrap = self.ydl.urlopen(bootstrap_url).read()
+        return read_bootstrap_info(bootstrap)
+
+    def _update_live_fragments(self, bootstrap_url, latest_fragment):
+        fragments_list = []
+        retries = 30
+        while (not fragments_list) and (retries > 0):
+            boot_info = self._get_bootstrap_from_url(bootstrap_url)
+            fragments_list = build_fragments_list(boot_info)
+            fragments_list = [f for f in fragments_list if f[1] > latest_fragment]
+            if not fragments_list:
+                # Retry after a while
+                time.sleep(5.0)
+                retries -= 1
+
+        if not fragments_list:
+            self.report_error('Failed to update fragments')
+
+        return fragments_list
+
+    def _parse_bootstrap_node(self, node, base_url):
+        if node.text is None:
+            bootstrap_url = compat_urlparse.urljoin(
+                base_url, node.attrib['url'])
+            boot_info = self._get_bootstrap_from_url(bootstrap_url)
+        else:
+            bootstrap_url = None
+            bootstrap = base64.b64decode(node.text)
+            boot_info = read_bootstrap_info(bootstrap)
+        return (boot_info, bootstrap_url)
+
     def real_download(self, filename, info_dict):
         man_url = info_dict['url']
         requested_bitrate = info_dict.get('tbr')
@@ -265,18 +303,13 @@ class F4mFD(FileDownloader):
 
         base_url = compat_urlparse.urljoin(man_url, media.attrib['url'])
         bootstrap_node = doc.find(_add_ns('bootstrapInfo'))
-        if bootstrap_node.text is None:
-            bootstrap_url = compat_urlparse.urljoin(
-                base_url, bootstrap_node.attrib['url'])
-            bootstrap = self.ydl.urlopen(bootstrap_url).read()
-        else:
-            bootstrap = base64.b64decode(bootstrap_node.text)
+        boot_info, bootstrap_url = self._parse_bootstrap_node(bootstrap_node, base_url)
+        live = boot_info['live']
         metadata_node = media.find(_add_ns('metadata'))
         if metadata_node is not None:
             metadata = base64.b64decode(metadata_node.text)
         else:
             metadata = None
-        boot_info = read_bootstrap_info(bootstrap)
 
         fragments_list = build_fragments_list(boot_info)
         if self.params.get('test', False):
@@ -301,7 +334,8 @@ class F4mFD(FileDownloader):
         (dest_stream, tmpfilename) = sanitize_open(tmpfilename, 'wb')
 
         write_flv_header(dest_stream)
-        write_metadata_tag(dest_stream, metadata)
+        if not live:
+            write_metadata_tag(dest_stream, metadata)
 
         # This dict stores the download progress, it's updated by the progress
         # hook
@@ -348,7 +382,8 @@ class F4mFD(FileDownloader):
         http_dl.add_progress_hook(frag_progress_hook)
 
         frags_filenames = []
-        for (seg_i, frag_i) in fragments_list:
+        while fragments_list:
+            seg_i, frag_i = fragments_list.pop(0)
             name = 'Seg%d-Frag%d' % (seg_i, frag_i)
             url = base_url + name
             if akamai_pv:
@@ -367,6 +402,10 @@ class F4mFD(FileDownloader):
                         break
             frags_filenames.append(frag_filename)
 
+            if not fragments_list and live and bootstrap_url:
+                fragments_list = self._update_live_fragments(bootstrap_url, frag_i)
+                self.to_screen('Updated available fragments: %d' % len(fragments_list))
+
         dest_stream.close()
 
         elapsed = time.time() - start