[vlmc-devel] [PATCH 4/4] VLCSource: Avoid deleting VmemRenderer too early

[yikei lu]

yes, if I don't apply this patch, I'll get only a half of a snapshot

2016-04-12 21:51 GMT+09:00 Hugo Beauzée-Luyssen <hugo at beauzee.fr>:
> On 04/12/2016 01:10 PM, Yikai Lu wrote:
>>
>> If we declare in a function like "VmemRenderer renderer( some values )"
>> just as we did before, it will be removed as soon as the function ends.
>> Since the renderer don't know how much time should be needed to render a
>> snapshot, we should keep it alive as long as possible.
>> ---
>>   src/Backend/VLC/VLCSource.cpp | 20 +++++++++++++-------
>>   src/Backend/VLC/VLCSource.h   |  4 +++-
>>   2 files changed, 16 insertions(+), 8 deletions(-)
>>
>> diff --git a/src/Backend/VLC/VLCSource.cpp b/src/Backend/VLC/VLCSource.cpp
>> index d38d12f..3257781 100644
>> --- a/src/Backend/VLC/VLCSource.cpp
>> +++ b/src/Backend/VLC/VLCSource.cpp
>> @@ -39,10 +39,16 @@ VLCSource::VLCSource( VLCBackend* backend, const
>> QString& path )
>>       , m_snapshot( nullptr )
>>       , m_isParsed( false )
>>       , m_nbFrames( 0 )
>> +    , m_vmemRenderer( nullptr )
>>   {
>>       m_media = ::VLC::Media( backend->vlcInstance(), path.toStdString(),
>> ::VLC::Media::FromPath );
>>   }
>>
>> +VLCSource::~VLCSource()
>> +{
>> +    delete m_vmemRenderer;
>> +}
>> +
>>   ::VLC::Media&
>>   VLCSource::media()
>>   {
>> @@ -63,7 +69,6 @@ VLCSource::preparse()
>>       Q_ASSERT( m_nbAudioTracks == 0 );
>>       Q_ASSERT( m_nbVideoTracks == 0 );
>>
>> -    VmemRenderer renderer( m_backend, this, nullptr );
>>       m_media.parse();
>>       m_length = m_media.duration();
>>       auto tracks = m_media.tracks();
>> @@ -85,7 +90,7 @@ VLCSource::preparse()
>>                   m_width = t.width();
>>                   m_height = t.height();
>>                   m_nbFrames = (int64_t)( (float)( m_length / 1000 ) *
>> m_fps );
>> -                computeSnapshot( renderer );
>> +                computeSnapshot();
>>               }
>>           }
>>           else if ( t.type() == ::VLC::MediaTrack::Type::Audio )
>> @@ -102,25 +107,26 @@ VLCSource::isParsed() const
>>   }
>>
>>   bool
>> -VLCSource::computeSnapshot( VmemRenderer& renderer )
>> +VLCSource::computeSnapshot()
>>   {
>>       Q_ASSERT( m_snapshot == nullptr );
>> -    renderer.start();
>> +    m_vmemRenderer = new VmemRenderer( m_backend, this, nullptr );
>> +    m_vmemRenderer->start();
>>       {
>>           QMutex mutex;
>>           QWaitCondition cond;
>> -        auto em = renderer.mediaPlayer().eventManager();
>> +        auto em = m_vmemRenderer->mediaPlayer().eventManager();
>>           em.onPositionChanged([&mutex, &cond](float pos) {
>>               QMutexLocker lock( &mutex );
>>               if ( pos > 0.2 )
>>                   cond.wakeAll();
>>           });
>>           QMutexLocker lock( &mutex );
>> -        renderer.setPosition( 0.3 );
>> +        m_vmemRenderer->setPosition( 0.3 );
>>           if ( cond.wait( &mutex, 2000 ) == false )
>>               return false;
>>       }
>> -    m_snapshot = renderer.waitSnapshot();
>> +    m_snapshot = m_vmemRenderer->waitSnapshot();
>>       return m_snapshot != nullptr;
>>   }
>>
>> diff --git a/src/Backend/VLC/VLCSource.h b/src/Backend/VLC/VLCSource.h
>> index 10a7d08..346adbe 100644
>> --- a/src/Backend/VLC/VLCSource.h
>> +++ b/src/Backend/VLC/VLCSource.h
>> @@ -40,6 +40,7 @@ class VLCSource : public ISource
>>   {
>>   public:
>>       VLCSource( VLCBackend* backend, const QString& path );
>> +    virtual ~VLCSource();
>>       virtual ISourceRenderer*    createRenderer( ISourceRendererEventCb*
>> callback );
>>       virtual bool                preparse();
>>       virtual bool                isParsed() const;
>> @@ -58,7 +59,7 @@ public:
>>       ::VLC::Media&               media();
>>
>>   private:
>> -    bool                        computeSnapshot( VmemRenderer& renderer
>> );
>> +    bool                        computeSnapshot();
>>
>>   private:
>>       VLCBackend*                 m_backend;
>> @@ -72,6 +73,7 @@ private:
>>       uint8_t*                    m_snapshot;
>>       bool                        m_isParsed;
>>       int64_t                     m_nbFrames;
>> +    VmemRenderer*               m_vmemRenderer;
>>   };
>>
>>
>>
> The renderer will stop the VLC::MediaPlayer upon destruction, so that
> shouldn't be a problem. Moreover, the waitSnapshot method ensure we block
> until the snapshot is computed, so the timing shouldn't be an issue.
> Did you encounter an issue related to this code?
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