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Add ASS/SSA subtitle support.
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Based on the final patch from Shawn King (thank you) in #9294 with the
following changes:-

- fixed the display area to line up with the video rect.
- only initialise libass when required.
- various additional NULL pointer checks and minor refactors.
- use SubtitleScreen::m_safeArea in the ass code.

I chose to use a compile time dependency on libass rather than create
another internal library version (and avoid the maintenance that it
would need) or use dynamic linking (extra complexity). As noted in
configure, the libass version (although not actually checked) needs to
be at least 0.9.10 - which is probably still too new for the libass
version packaged with most distros.

Closes #9294
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Mark Kendall committed May 3, 2011
1 parent 4ec47f8 commit bfeabee
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Showing 4 changed files with 321 additions and 0 deletions.
10 changes: 10 additions & 0 deletions mythtv/configure
View file
Expand Up @@ -125,6 +125,7 @@ Advanced options (experts only):
--disable-opengl-video disable OpenGL based video display
--disable-quartz-video disable Mac OS X CoreVideo based video display
--disable-directfb disable DirectFB (Linux non-X11 video)
--disable-libass disable libass SSA/ASS subtitle support
--enable-mac-bundle produce standalone OS X apps (e.g. mythfrontend.app)
Expand Down Expand Up @@ -1976,6 +1977,7 @@ enable hdpvr
enable iptv
enable ivtv
enable lamemp3
enable libass
enable libxml2
enable libudf
enable lirc
Expand Down Expand Up @@ -4045,6 +4047,9 @@ fi
enabled libfftw3 && check_lib2 fftw3.h fftw_init_threads -lfftw3_threads -lfftw3f -lfftw3 ||
disable libfftw3

# ass_flush_events was added in 0.9.10
enabled libass && check_lib2 ass/ass.h ass_flush_events -lass || disable libass

if enabled libxml2 ; then
if pkg-config --exists libxml-2.0 ; then
libxml2_path=`pkg-config --cflags-only-I libxml-2.0|sed -n "s/-I\([^ ]*\) *$/\1/p"`
Expand Down Expand Up @@ -4472,6 +4477,7 @@ fi
echo "DXVA2 support ${dxva2-no}"
fi
echo "MHEG support ${mheg}"
echo "libass subtitle support ${libass-no}"
echo
fi

Expand Down Expand Up @@ -4761,6 +4767,10 @@ if enabled mheg; then
append CCONFIG "using_mheg"
fi

if enabled libass; then
append CCONFIG "using_libass"
fi

if enabled appleremote; then
append CONFIG_DEFINES "USING_APPLEREMOTE"
fi
Expand Down
5 changes: 5 additions & 0 deletions mythtv/libs/libmythtv/libmythtv.pro
View file
Expand Up @@ -297,6 +297,11 @@ using_frontend {
LIBS += -lcrystalhd
}

using_libass {
DEFINES += USING_LIBASS
LIBS += -lass
}

macx {
HEADERS += privatedecoder_vda.h privatedecoder_vda_defs.h
SOURCES += privatedecoder_vda.cpp
Expand Down
283 changes: 283 additions & 0 deletions mythtv/libs/libmythtv/subtitlescreen.cpp
View file
Expand Up @@ -30,11 +30,22 @@ SubtitleScreen::SubtitleScreen(MythPlayer *player, const char * name,
m_708fontSizes[1] = 45;
m_708fontSizes[2] = 60;
m_removeHTML.setMinimal(true);

#ifdef USING_LIBASS
m_assLibrary = NULL;
m_assRenderer = NULL;
m_assTrackNum = -1;
m_assTrack = NULL;
m_assFontCount = 0;
#endif
}

SubtitleScreen::~SubtitleScreen(void)
{
ClearAllSubtitles();
#ifdef USING_LIBASS
CleanupAssLibrary();
#endif
}

void SubtitleScreen::EnableSubtitles(int type)
Expand Down Expand Up @@ -96,6 +107,10 @@ void SubtitleScreen::ClearAllSubtitles(void)
{
ClearNonDisplayedSubtitles();
ClearDisplayedSubtitles();
#ifdef USING_LIBASS
if (m_assTrack)
ass_flush_events(m_assTrack);
#endif
}

void SubtitleScreen::ClearNonDisplayedSubtitles(void)
Expand Down Expand Up @@ -292,9 +307,19 @@ void SubtitleScreen::DisplayAVSubtitles(void)
QString("AV Sub was %1 ms late").arg(late));
}
}
#ifdef USING_LIBASS
else if (displaysub && rect->type == SUBTITLE_ASS)
{
InitialiseAssTrack(m_player->GetDecoder()->GetTrack(kTrackTypeSubtitle));
AddAssEvent(rect->ass);
}
#endif
}
m_subreader->FreeAVSubtitle(subtitle);
}
#ifdef USING_LIBASS
RenderAssTrack(currentFrame->timecode);
#endif
subs->lock.unlock();
}

Expand Down Expand Up @@ -1028,3 +1053,261 @@ MythFontProperties* SubtitleScreen::Get708Font(CC708CharacterAttribute attr)

return mythfont;
}

#ifdef USING_LIBASS
static void myth_libass_log(int level, const char *fmt, va_list vl, void *ctx)
{
static QString full_line("libass:");
static const int msg_len = 255;
static QMutex string_lock;
uint verbose_level = 0;

switch (level)
{
case 0: //MSGL_FATAL
verbose_level = VB_IMPORTANT;
break;
case 1: //MSGL_ERR
case 2: //MSGL_WARN
case 4: //MSGL_INFO
verbose_level = VB_GENERAL;
break;
case 6: //MSGL_V
case 7: //MSGL_DBG2
default:
return;
}

if (!VERBOSE_LEVEL_CHECK(verbose_level))
return;

string_lock.lock();

char str[msg_len+1];
int bytes = vsnprintf(str, msg_len+1, fmt, vl);
// check for truncated messages and fix them
if (bytes > msg_len)
{
VERBOSE(VB_IMPORTANT, QString("libASS log output truncated %1 of %2 bytes written")
.arg(msg_len).arg(bytes));
str[msg_len-1] = '\n';
}

full_line += QString(str);
if (full_line.endsWith("\n"))
{
full_line.truncate(full_line.length() - 1);
VERBOSE(verbose_level, full_line);
full_line.truncate(0);
}
string_lock.unlock();
}

bool SubtitleScreen::InitialiseAssLibrary(void)
{
if (m_assLibrary && m_assRenderer)
return true;

if (!m_assLibrary)
{
m_assLibrary = ass_library_init();
if (!m_assLibrary)
return false;

ass_set_message_cb(m_assLibrary, myth_libass_log, NULL);
ass_set_extract_fonts(m_assLibrary, true);
VERBOSE(VB_PLAYBACK, LOC + QString("Initialised libass object."));
}

LoadAssFonts();

if (!m_assRenderer)
{
m_assRenderer = ass_renderer_init(m_assLibrary);
if (!m_assRenderer)
return false;

ass_set_fonts(m_assRenderer, NULL, "sans-serif", 1, NULL, 1);
ass_set_hinting(m_assRenderer, ASS_HINTING_LIGHT);
VERBOSE(VB_PLAYBACK, LOC + QString("Initialised libass renderer."));
}

return true;
}

void SubtitleScreen::LoadAssFonts(void)
{
if (!m_assLibrary || !m_player)
return;

uint count = m_player->GetDecoder()->GetTrackCount(kTrackTypeAttachment);
if (m_assFontCount == count)
return;

ass_clear_fonts(m_assLibrary);
m_assFontCount = 0;

// TODO these need checking and/or reinitialising after a stream change
for (uint i = 0; i < count; ++i)
{
QByteArray filename;
QByteArray font;
m_player->GetDecoder()->GetAttachmentData(i, filename, font);
ass_add_font(m_assLibrary, filename.data(), font.data(), font.size());
VERBOSE(VB_PLAYBACK, LOC + QString("Retrieved font '%1'")
.arg(filename.constData()));
m_assFontCount++;
}
}

void SubtitleScreen::CleanupAssLibrary(void)
{
CleanupAssTrack();

if (m_assRenderer)
ass_renderer_done(m_assRenderer);
m_assRenderer = NULL;

if (m_assLibrary)
{
ass_clear_fonts(m_assLibrary);
m_assFontCount = 0;
ass_library_done(m_assLibrary);
}
m_assLibrary = NULL;
}

void SubtitleScreen::InitialiseAssTrack(int tracknum)
{
if (!InitialiseAssLibrary() || !m_player)
return;

if (tracknum == m_assTrackNum && m_assTrack)
return;

LoadAssFonts();
CleanupAssTrack();
m_assTrack = ass_new_track(m_assLibrary);
m_assTrackNum = tracknum;

QByteArray header = m_player->GetDecoder()->GetSubHeader(tracknum);
if (!header.isNull())
ass_process_codec_private(m_assTrack, header.data(), header.size());

m_safeArea = m_player->getVideoOutput()->GetMHEGBounds();
ResizeAssRenderer();
}

void SubtitleScreen::CleanupAssTrack(void)
{
if (m_assTrack)
ass_free_track(m_assTrack);
m_assTrack = NULL;
}

void SubtitleScreen::AddAssEvent(char *event)
{
if (m_assTrack && event)
ass_process_data(m_assTrack, event, strlen(event));
}

void SubtitleScreen::ResizeAssRenderer(void)
{
// TODO this probably won't work properly for anamorphic content and XVideo
ass_set_frame_size(m_assRenderer, m_safeArea.width(), m_safeArea.height());
ass_set_margins(m_assRenderer, 0, 0, 0, 0);
ass_set_use_margins(m_assRenderer, true);
ass_set_font_scale(m_assRenderer, 1.0);
}

void SubtitleScreen::RenderAssTrack(uint64_t timecode)
{
if (!m_player || !m_assRenderer || !m_assTrack)
return;

VideoOutput *vo = m_player->getVideoOutput();
if (!vo )
return;

QRect oldscreen = m_safeArea;
m_safeArea = vo->GetMHEGBounds();
if (oldscreen != m_safeArea)
ResizeAssRenderer();

int changed = 0;
ASS_Image *images = ass_render_frame(m_assRenderer, m_assTrack,
timecode, &changed);
if (!changed)
return;

MythPainter *osd_painter = vo->GetOSDPainter();
if (!osd_painter)
return;

int count = 0;
DeleteAllChildren();
SetRedraw();
while (images)
{
if (images->w == 0 || images->h == 0)
{
images = images->next;
continue;
}

uint8_t alpha = images->color & 0xFF;
uint8_t blue = images->color >> 8 & 0xFF;
uint8_t green = images->color >> 16 & 0xFF;
uint8_t red = images->color >> 24 & 0xFF;

if (alpha == 255)
{
images = images->next;
continue;
}

QSize img_size(images->w, images->h);
QRect img_rect(images->dst_x,images->dst_y,
images->w, images->h);
QImage qImage(img_size, QImage::Format_ARGB32);
qImage.fill(0x00000000);

unsigned char *src = images->bitmap;
for (int y = 0; y < images->h; ++y)
{
for (int x = 0; x < images->w; ++x)
{
uint8_t value = src[x];
if (value)
{
uint32_t pixel = (value * (255 - alpha) / 255 << 24) |
(red << 16) | (green << 8) | blue;
qImage.setPixel(x, y, pixel);
}
}
src += images->stride;
}

MythImage* image = NULL;
MythUIImage *uiimage = NULL;

if (osd_painter)
image = osd_painter->GetFormatImage();

if (image)
{
image->Assign(qImage);
QString name = QString("asssub%1").arg(count);
uiimage = new MythUIImage(this, name);
if (uiimage)
{
m_refreshArea = true;
uiimage->SetImage(image);
uiimage->SetArea(MythRect(img_rect));
}
}
images = images->next;
count++;
}
}
#endif // USING_LIBASS

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