Extend IPTV/HLS/M3U tag parsing

Add parsing of tag EXT-X-DISCONTINUITY-SEQUENCE.
Previously, this tag was erroneously parsed and
executed as EXT-X-DISCONTINUITY. This then caused
continuous downloading at maximum bandwidth.

Add parsing of tags EXT-X-INDEPENDENT-SEGMENTS.
There is no implementation added but this does
prevent parsing failure.

Allow EXT-X-VERSION tag values from 1 to 7.
There is no implementation added but this does
prevent parsing failure.

Refs #936

mythtv/libs/libmythtv/HLS/m3u.cpp

@@ -105,10 +105,10 @@ namespace M3U
             return false;
         }
 
-        if (version <= 0 || version > 3)
+        if (version < 1 || version > 7)
         {
             LOG(VB_RECORD, LOG_ERR, loc +
-                QString("#EXT-X-VERSION is %1, but we only understand 0 through 3")
+                QString("#EXT-X-VERSION is %1, but we only understand 1 to 7")
                 .arg(version));
             return false;
         }
@@ -341,6 +341,11 @@ namespace M3U
             path = DecodedURI(uri.remove(QChar(QLatin1Char('"'))));
             iv = ParseAttributes(line, "IV");
         }
+        else if (attr.startsWith(QLatin1String("SAMPLE-AES")))
+        {
+            LOG(VB_RECORD, LOG_ERR, loc + "encryption SAMPLE-AES not supported.");
+            return false;
+        }
 #endif
         else
         {
@@ -405,6 +410,30 @@ namespace M3U
         return true;
     }
 
+    bool ParseDiscontinuitySequence(const QString& line, const QString& loc, int &discontinuity_sequence)
+    {
+        /*
+         * The EXT-X-DISCONTINUITY-SEQUENCE tag allows synchronization between
+         * different Renditions of the same Variant Stream or different Variant
+         * Streams that have EXT-X-DISCONTINUITY tags in their Media Playlists.
+         *
+         * Its format is:
+         *
+         * #EXT-X-DISCONTINUITY-SEQUENCE:<number>
+         *
+         * where number is a decimal-integer
+         */
+        if (!ParseDecimalValue(line, discontinuity_sequence))
+        {
+            LOG(VB_RECORD, LOG_ERR, loc + "expected #EXT-X-DISCONTINUITY-SEQUENCE:<s>");
+            return false;
+        }
+
+        LOG(VB_RECORD, LOG_DEBUG, loc + QString("#EXT-X-DISCONTINUITY-SEQUENCE %1")
+            .arg(line));
+        return true;
+    }
+
     bool ParseDiscontinuity(const QString& line, const QString& loc)
     {
         /* Not handled, never seen so far */
@@ -425,4 +454,23 @@ namespace M3U
         return true;
     }
 
-} // Namespace M3U
+    bool ParseIndependentSegments(const QString& line, const QString& loc)
+    {
+        /* #EXT-X-INDEPENDENT-SEGMENTS
+         *
+         * The EXT-X-INDEPENDENT-SEGMENTS tag indicates that all media samples
+         * in a Media Segment can be decoded without information from other
+         * segments.  It applies to every Media Segment in the Playlist.
+         *
+         * Its format is:
+         *
+         * #EXT-X-INDEPENDENT-SEGMENTS
+         */
+
+        // Not handled yet
+        LOG(VB_RECORD, LOG_DEBUG, loc + QString("#EXT-X-INDEPENDENT-SEGMENTS %1")
+            .arg(line));
+        return true;
+    }
+
+} // namespace M3U

mythtv/libs/libmythtv/HLS/m3u.h

@@ -4,6 +4,7 @@
 #include <cinttypes>
 
 #include <QDateTime>
+#include <QString>
 
 namespace M3U
 {
@@ -30,8 +31,11 @@ namespace M3U
 			      QDateTime &date);
     bool ParseAllowCache(const QString& line, const QString& loc,
 			 bool& do_cache);
+    bool ParseDiscontinuitySequence(const QString& line, const QString& loc,
+            int &discontinuity_sequence);
     bool ParseDiscontinuity(const QString& line, const QString& loc);
     bool ParseEndList(const QString& loc, bool& is_vod);
+    bool ParseIndependentSegments(const QString& line, const QString& loc);
 }
 
 #endif // MYTHTV_M3U_H

mythtv/libs/libmythtv/recorders/HLS/HLSReader.cpp

@@ -9,7 +9,8 @@
 #include "HLSReader.h"
 #include "HLS/m3u.h"
 
-#define LOC QString("%1: ").arg(m_curstream ? m_curstream->M3U8Url() : "HLSReader")
+#define LOC QString("HLSReader[%1]%2: ")\
+.arg(m_inputId).arg(m_curstream ? "(" + m_curstream->M3U8Url() + ")" : "")
 
 /**
  * Handles relative URLs without breaking URI encoded parameters by avoiding
@@ -264,7 +265,11 @@ bool HLSReader::IsValidPlaylist(QTextStream & text)
 {
     /* Parse stream and search for
      * EXT-X-TARGETDURATION or EXT-X-STREAM-INF tag, see
-     * http://tools.ietf.org/html/draft-pantos-http-live-streaming-04#page-8 */
+     * http://tools.ietf.org/html/draft-pantos-http-live-streaming-04#page-8
+     *
+     * Updated with latest available version from 2017, see
+     * https://datatracker.ietf.org/doc/html/rfc8216
+     */
     QString line = text.readLine();
     if (!line.startsWith((const char*)"#EXTM3U"))
         return false;
@@ -509,12 +514,25 @@ bool HLSReader::ParseM3U8(const QByteArray& buffer, HLSRecStream* stream)
                     return false;
                 hls->SetCache(do_cache);
             }
+            else if (line.startsWith(QLatin1String("#EXT-X-DISCONTINUITY-SEQUENCE")))
+            {
+                int sequence = 0;
+                if (!M3U::ParseDiscontinuitySequence(line, StreamURL(), sequence))
+                    return false;
+                SetDiscontinuitySequence(sequence);
+            }
             else if (line.startsWith(QLatin1String("#EXT-X-DISCONTINUITY")))
             {
                 if (!M3U::ParseDiscontinuity(line, StreamURL()))
                     return false;
                 ResetSequence();
             }
+            else if (line.startsWith(QLatin1String("#EXT-X-INDEPENDENT-SEGMENTS")))
+            {
+                if (!M3U::ParseIndependentSegments(line, StreamURL()))
+                    return false;
+                // Not handled yet
+            }
             else if (line.startsWith(QLatin1String("#EXT-X-VERSION")))
             {
                 int version2 = 0;

mythtv/libs/libmythtv/recorders/HLS/HLSReader.h

@@ -40,7 +40,7 @@ class MTV_PUBLIC  HLSReader
     using StreamContainer = QMap<QString, HLSRecStream* >;
     using SegmentContainer = QVector<HLSRecSegment>;
 
-    HLSReader(void) = default;
+    HLSReader(int inputId) { m_inputId = inputId; };
     ~HLSReader(void);
 
     bool Open(const QString & m3u, int bitrate_index = 0);
@@ -56,6 +56,7 @@ class MTV_PUBLIC  HLSReader
     void ResetStream(void)
       { QMutexLocker lock(&m_streamLock); m_curstream = nullptr; }
     void ResetSequence(void) { m_curSeq = -1; }
+    void SetDiscontinuitySequence(int s) { m_sequence = s; }
 
     QString StreamURL(void) const
     { return QString("%1").arg(m_curstream ? m_curstream->M3U8Url() : ""); }
@@ -106,7 +107,7 @@ class MTV_PUBLIC  HLSReader
     bool               m_fatal          {false};
     bool               m_cancel         {false};
     bool               m_throttle       {true};
-                     // only print one time that the media is encrypted
+    // Only print one time that the media is encrypted
     bool               m_aesMsg         {false};
 
     HLSPlaylistWorker *m_playlistWorker {nullptr};
@@ -127,6 +128,11 @@ class MTV_PUBLIC  HLSReader
     int                m_slowCnt        {0};
     QByteArray         m_buffer;
     QMutex             m_bufLock;
+
+    int                m_sequence       {0};     // Discontinuity sequence number
+
+    // Log message
+    int                m_inputId        {0};
 };
 
 #endif // HLS_READER_H

mythtv/libs/libmythtv/recorders/hlsstreamhandler.cpp

@@ -101,7 +101,7 @@ HLSStreamHandler::HLSStreamHandler(const IPTVTuningData& tuning, int inputid)
     : IPTVStreamHandler(tuning, inputid)
 {
     LOG(VB_GENERAL, LOG_INFO, LOC + "ctor");
-    m_hls        = new HLSReader();
+    m_hls        = new HLSReader(m_inputId);
     m_readbuffer = new uint8_t[BUFFER_SIZE];
 }