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Public Member Functions | Static Public Member Functions | Protected Member Functions | Protected Attributes

MovieVideoCursor Class Reference

A MovieVideo is actually any source that provides a sequence of video frames. More...

#include "movieVideoCursor.h"

Inheritance diagram for MovieVideoCursor:
TypedWritableReferenceCount TypedWritable ReferenceCount TypedObject MemoryBase MemoryBase InkblotVideoCursor

List of all members.

Public Member Functions

 MovieVideoCursor (MovieVideo *src)
 This constructor returns a null video stream --- a stream of plain blue and white frames that last one second each.
bool aborted () const
 Returns true if the video has aborted prematurely.
bool can_seek () const
 Returns true if the movie can seek.
bool can_seek_fast () const
 Returns true if seek operations are constant time.
virtual void fetch_into_bitbucket (double time)
 Discards the next video frame.
virtual void fetch_into_buffer (double time, unsigned char *block, bool bgra)
 Reads the specified video frame into the supplied BGR or BGRA buffer.
virtual void fetch_into_texture (double time, Texture *t, int page)
virtual void fetch_into_texture_alpha (double time, Texture *t, int page, int alpha_src)
 Reads the specified video frame into the alpha channel of the supplied texture.
virtual void fetch_into_texture_rgb (double time, Texture *t, int page)
 Reads the specified video frame into the RGB channels of the supplied texture.
virtual TypeHandle force_init_type ()
int get_num_components () const
 Returns 4 if the movie has an alpha channel, 3 otherwise.
virtual TypeHandle get_type () const
double last_start () const
 Returns the start time of the last frame you read.
double length () const
 Returns the length of the movie.
double next_start () const
 Returns the start time of the next frame you can read.
 PT (MovieVideo) get_source() const
bool ready () const
 Returns true if the cursor is a streaming source, and if a video frame is ready to be read.
void setup_texture (Texture *tex) const
 Set up the specified Texture object to contain content from this movie.
int size_x () const
 Get the horizontal size of the movie.
int size_y () const
 Get the vertical size of the movie.
bool streaming () const
 Returns true if the video frames are being "pushed" at us by something that operates at its own speed - for example, a webcam.

Static Public Member Functions

static TypeHandle get_class_type ()
static void init_type ()

Protected Member Functions

 PT (MovieVideo) _source

Protected Attributes

bool _aborted
bool _can_seek
bool _can_seek_fast
double _last_start
double _length
double _next_start
int _num_components
bool _ready
int _size_x
int _size_y
bool _streaming

Detailed Description

A MovieVideo is actually any source that provides a sequence of video frames.

That could include an AVI file, a digital camera, or an internet TV station. A MovieVideoCursor is a handle that lets you read data sequentially from a MovieVideo.

Thread safety: each individual MovieVideoCursor must be owned and accessed by a single thread. It is OK for two different threads to open the same file at the same time, as long as they use separate MovieVideoCursor objects.

Definition at line 37 of file movieVideoCursor.h.


Constructor & Destructor Documentation

MovieVideoCursor::MovieVideoCursor ( MovieVideo src)

This constructor returns a null video stream --- a stream of plain blue and white frames that last one second each.

To get more interesting video, you need to construct a subclass of this class.

Definition at line 31 of file movieVideoCursor.cxx.


Member Function Documentation

bool MovieVideoCursor::aborted ( ) const [inline]

Returns true if the video has aborted prematurely.

For example, this could occur if the Movie was actually an internet TV station, and the connection was lost. Reaching the normal end of the video does not constitute an 'abort' condition.

Definition at line 129 of file movieVideoCursor.I.

bool MovieVideoCursor::can_seek ( ) const [inline]

Returns true if the movie can seek.

If this is true, seeking is still not guaranteed to be fast: for some movies, seeking is implemented by rewinding to the beginning and then fast-forwarding to the desired location. Even if the movie cannot seek, the fetch methods can still advance to an arbitrary location by reading frames and discarding them. However, to move backward, can_seek must return true.

Definition at line 105 of file movieVideoCursor.I.

bool MovieVideoCursor::can_seek_fast ( ) const [inline]

Returns true if seek operations are constant time.

Definition at line 115 of file movieVideoCursor.I.

void MovieVideoCursor::fetch_into_bitbucket ( double  time) [virtual]

Discards the next video frame.

Still sets last_start and next_start.

See fetch_into_buffer for more details.

Definition at line 103 of file movieVideoCursor.cxx.

References fetch_into_buffer().

void MovieVideoCursor::fetch_into_buffer ( double  time,
unsigned char *  data,
bool  bgra 
) [virtual]

Reads the specified video frame into the supplied BGR or BGRA buffer.

The frame's begin and end times are stored in last_start and next_start.

If the movie reports that it can_seek, you may also specify a timestamp less than next_start. Otherwise, you may only specify a timestamp greater than or equal to next_start.

If the movie reports that it can_seek, it doesn't mean that it can do so quickly. It may have to rewind the movie and then fast forward to the desired location. Only if can_seek_fast returns true can it seek rapidly.

Reimplemented in InkblotVideoCursor.

Definition at line 282 of file movieVideoCursor.cxx.

Referenced by fetch_into_bitbucket(), fetch_into_texture_alpha(), and fetch_into_texture_rgb().

void MovieVideoCursor::fetch_into_texture_alpha ( double  time,
Texture t,
int  page,
int  alpha_src 
) [virtual]

Reads the specified video frame into the alpha channel of the supplied texture.

The RGB channels of the texture are not touched.

See fetch_into_buffer for more details.

Definition at line 170 of file movieVideoCursor.cxx.

References fetch_into_buffer(), Texture::get_component_width(), Texture::get_expected_ram_page_size(), Texture::get_num_components(), Texture::get_x_size(), Texture::get_y_size(), Texture::modify_ram_image(), size_x(), and size_y().

void MovieVideoCursor::fetch_into_texture_rgb ( double  time,
Texture t,
int  page 
) [virtual]

Reads the specified video frame into the RGB channels of the supplied texture.

The alpha channel of the texture is not touched.

See fetch_into_buffer for more details.

Definition at line 227 of file movieVideoCursor.cxx.

References fetch_into_buffer(), Texture::get_component_width(), Texture::get_expected_ram_page_size(), Texture::get_num_components(), Texture::get_x_size(), Texture::get_y_size(), Texture::modify_ram_image(), size_x(), and size_y().

int MovieVideoCursor::get_num_components ( ) const [inline]

Returns 4 if the movie has an alpha channel, 3 otherwise.

Definition at line 52 of file movieVideoCursor.I.

Referenced by setup_texture().

double MovieVideoCursor::last_start ( ) const [inline]

Returns the start time of the last frame you read.

MovieVideoCursor streams have variable frame rates. Each frame will specify how long it is to be displayed. These lengths may not be equal from frame to frame.

Definition at line 143 of file movieVideoCursor.I.

double MovieVideoCursor::length ( ) const [inline]

Returns the length of the movie.

Some kinds of Movie, such as internet TV station, might not have a predictable length. In that case, the length will be set to a very large number: 1.0E10. If the internet TV station goes offline, the video or audio stream will set its abort flag. Reaching the end of the movie (ie, the specified length) normally does not cause the abort flag to be set.

The video and audio streams produced by get_video and get_audio are always of unlimited duration - you can always read another video frame or another audio sample. This is true even if the specified length is reached, or an abort is flagged. If either stream runs out of data, it will synthesize blank video frames and silent audio samples as necessary to satisfy read requests.

Some AVI files have incorrect length values encoded into them - usually, they're a second or two long or short. When playing such an AVI using the Movie class, you may see a slightly truncated video, or a slightly elongated video (padded with black frames). There are utilities out there to fix the length values in AVI files.

Definition at line 88 of file movieVideoCursor.I.

double MovieVideoCursor::next_start ( ) const [inline]

Returns the start time of the next frame you can read.

MovieVideoCursor streams have variable frame rates. Each frame will specify how long it is to be displayed. These lengths may not be equal from frame to frame.

Definition at line 157 of file movieVideoCursor.I.

bool MovieVideoCursor::ready ( ) const [inline]

Returns true if the cursor is a streaming source, and if a video frame is ready to be read.

For non- streaming sources, this is always false.

Definition at line 190 of file movieVideoCursor.I.

void MovieVideoCursor::setup_texture ( Texture tex) const

Set up the specified Texture object to contain content from this movie.

This should be called once, not every frame.

Definition at line 82 of file movieVideoCursor.cxx.

References get_num_components(), Texture::get_textures_power_2(), Texture::set_pad_size(), Texture::setup_texture(), size_x(), size_y(), and Texture::up_to_power_2().

int MovieVideoCursor::size_x ( ) const [inline]

Get the horizontal size of the movie.

Definition at line 31 of file movieVideoCursor.I.

Referenced by InkblotVideoCursor::fetch_into_buffer(), fetch_into_texture_alpha(), fetch_into_texture_rgb(), and setup_texture().

int MovieVideoCursor::size_y ( ) const [inline]

Get the vertical size of the movie.

Definition at line 41 of file movieVideoCursor.I.

Referenced by InkblotVideoCursor::fetch_into_buffer(), fetch_into_texture_alpha(), fetch_into_texture_rgb(), and setup_texture().

bool MovieVideoCursor::streaming ( ) const [inline]

Returns true if the video frames are being "pushed" at us by something that operates at its own speed - for example, a webcam.

In this case, the frames come when they're ready to come. Attempting to read too soon will produce nothing, reading too late will cause frames to be dropped. In this case, the ready flag can be used to determine whether or not a frame is ready for reading.

When streaming, you should still pay attention to last_start, but the value of next_start is only a guess.

Definition at line 178 of file movieVideoCursor.I.


The documentation for this class was generated from the following files:
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