MythUtil: add a --calctracklen option

This command will decode a music track to determin it's exact length and will
then update the database and send a MUSIC_METADATA_CHANGED event if it changed.

Example:-
mythutil --calctracklen --songid='1234'

mythtv/programs/mythutil/commandlineparser.cpp

@@ -155,6 +155,9 @@ void MythUtilCommandLineParser::LoadArguments(void)
         << add("--extractimage", "extractimage", false,
                 "Extract an embedded image from a tracks tag and cache it in the AlbumArt storage group", "")
                 ->SetGroup("Metadata Reading/Writing")
+        << add("--calctracklen", "calctracklen", false,
+                "Decode a track to determine its exact length", "")
+                ->SetGroup("Metadata Reading/Writing")
         );
 
     // mpegutils.cpp
@@ -230,6 +233,8 @@ void MythUtilCommandLineParser::LoadArguments(void)
             ->SetChildOf("extractimage");
     add("--imagetype", "imagetype", "", "Type of image to extract (front, back, cd, inlay, unknown)", "")
             ->SetChildOf("extractimage");
+    add("--songid", "songid", "", "ID of track to determine the length", "")
+            ->SetChildOf("calctracklen");
 
     // Generic Options used by more than one utility
     addRecording();

mythtv/programs/mythutil/musicmetautils.cpp

@@ -11,6 +11,11 @@
 #include "musicfilescanner.h"
 #include "musicutils.h"
 
+extern "C" {
+#include <libavformat/avformat.h>
+#include <libavcodec/avcodec.h>
+}
+
 // mythutils headers
 #include "commandlineparser.h"
 #include "musicmetautils.h"
@@ -186,9 +191,129 @@ static int ScanMusic(const MythUtilCommandLineParser &cmdline)
     return GENERIC_EXIT_OK;
 }
 
+static int CalcTrackLength(const MythUtilCommandLineParser &cmdline)
+{
+    if (cmdline.toString("songid").isEmpty())
+    {
+        LOG(VB_GENERAL, LOG_ERR, "Missing --songid option");
+        return GENERIC_EXIT_INVALID_CMDLINE;
+    }
+
+    int songID = cmdline.toInt("songid");
+
+    MusicMetadata *mdata = MusicMetadata::createFromID(songID);
+    if (!mdata)
+    {
+        LOG(VB_GENERAL, LOG_ERR, QString("Cannot find metadata for trackid: %1").arg(songID));
+        return GENERIC_EXIT_NOT_OK;
+    }
+
+    QString musicFile = mdata->getLocalFilename();
+
+    if (musicFile.isEmpty() || !QFile::exists(musicFile))
+    {
+        LOG(VB_GENERAL, LOG_ERR, QString("Cannot find file for trackid: %1").arg(songID));
+        return GENERIC_EXIT_NOT_OK;
+    }
+
+    av_register_all();
+
+    AVFormatContext *inputFC = NULL;
+    AVInputFormat *fmt = NULL;
+
+    // Open track
+    LOG(VB_GENERAL, LOG_DEBUG, QString("CalcTrackLength: Opening '%1'")
+            .arg(musicFile));
+
+    QByteArray inFileBA = musicFile.toLocal8Bit();
+
+    int ret = avformat_open_input(&inputFC, inFileBA.constData(), fmt, NULL);
+
+    if (ret)
+    {
+        LOG(VB_GENERAL, LOG_ERR, "CalcTrackLength: Couldn't open input file" +
+                                  ENO);
+        return GENERIC_EXIT_NOT_OK;
+    }
+
+    // Getting stream information
+    ret = avformat_find_stream_info(inputFC, NULL);
+
+    if (ret < 0)
+    {
+        LOG(VB_GENERAL, LOG_ERR,
+            QString("CalcTrackLength: Couldn't get stream info, error #%1").arg(ret));
+        avformat_close_input(&inputFC);
+        inputFC = NULL;
+        return GENERIC_EXIT_NOT_OK;;
+    }
+
+    uint duration = 0;
+    long long time = 0;
+
+    for (uint i = 0; i < inputFC->nb_streams; i++)
+    {
+        AVStream *st = inputFC->streams[i];
+        char buf[256];
+
+        avcodec_string(buf, sizeof(buf), st->codec, false);
+
+        switch (inputFC->streams[i]->codec->codec_type)
+        {
+            case AVMEDIA_TYPE_AUDIO:
+            {
+                AVPacket pkt;
+                av_init_packet(&pkt);
+
+                while (av_read_frame(inputFC, &pkt) >= 0)
+                {
+                    if (pkt.stream_index == (int)i)
+                        time = time + pkt.duration;
+
+                    av_free_packet(&pkt);
+                }
+
+                duration = time * av_q2d(inputFC->streams[i]->time_base);
+                break;
+            }
+
+            default:
+                LOG(VB_GENERAL, LOG_ERR,
+                    QString("Skipping unsupported codec %1 on stream %2")
+                        .arg(inputFC->streams[i]->codec->codec_type).arg(i));
+                break;
+        }
+    }
+
+    // Close input file
+    avformat_close_input(&inputFC);
+    inputFC = NULL;
+
+    if (mdata->Length() / 1000 != duration)
+    {
+        LOG(VB_GENERAL, LOG_INFO, QString("The length of this track in the database was %1s "
+                                          "it is now %2s").arg(mdata->Length() / 1000).arg(duration));
+
+        // update the track length in the database
+        mdata->setLength(duration * 1000);
+        mdata->dumpToDatabase();
+
+        // tell any clients that the metadata for this track has changed
+        gCoreContext->SendMessage(QString("MUSIC_METADATA_CHANGED %1").arg(songID));
+    }
+    else
+    {
+        LOG(VB_GENERAL, LOG_INFO, QString("The length of this track is unchanged %1s")
+                                          .arg(mdata->Length() / 1000));
+    }
+
+    return GENERIC_EXIT_OK;
+}
+
 void registerMusicUtils(UtilMap &utilMap)
 {
     utilMap["updatemeta"] = &UpdateMeta;
     utilMap["extractimage"] = &ExtractImage;
     utilMap["scanmusic"] = &ScanMusic;
+    utilMap["calctracklen"] = &CalcTrackLength;
 }