Class: FLV::FLVVideoTag

Inherits:
FLVTag
  • Object
show all
Defined in:
lib/flv/video_tag.rb

Constant Summary collapse

H263VIDEOPACKET = 
2
SCREENVIDEOPACKET = 
3
ON2VP6 = 
4
KEYFRAME = 
1
INTERFRAME = 
2
DISPOSABLEINTERFRAME = 
3

Constants inherited from FLVTag

FLV::FLVTag::AUDIO, FLV::FLVTag::META, FLV::FLVTag::UNDEFINED, FLV::FLVTag::VIDEO

Instance Attribute Summary collapse

Attributes inherited from FLVTag

#byte_offset, #tag_type, #timestamp

Instance Method Summary collapse

Methods inherited from FLVTag

#data, #data_size, #info, #initialize, #serialize, #size, type2name

Constructor Details

This class inherits a constructor from FLV::FLVTag

Instance Attribute Details

#codec_id ⇒ Object (readonly)

Returns the value of attribute codec_id.



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# File 'lib/flv/video_tag.rb', line 40

def codec_id
  @codec_id
end

#frame_type ⇒ Object (readonly)

Returns the value of attribute frame_type.



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# File 'lib/flv/video_tag.rb', line 40

def frame_type
  @frame_type
end

#height ⇒ Object (readonly)

Returns the value of attribute height.



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# File 'lib/flv/video_tag.rb', line 40

def height
  @height
end

#width ⇒ Object (readonly)

Returns the value of attribute width.



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# File 'lib/flv/video_tag.rb', line 40

def width
  @width
end

Instance Method Details

#after_initialize(new_object) ⇒ Object 



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# File 'lib/flv/video_tag.rb', line 45

def after_initialize(new_object)
  @tag_type = VIDEO
  read_header
end

#inspect ⇒ Object 



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# File 'lib/flv/video_tag.rb', line 104

def inspect
  out = super
  out << "frame_type: #{%w{ Keyframe Interframe DisposableInterframe }[@frame_type]}"
  out << "codec_id: #{@codec_id}"
  out << "width: #{@width}"
  out << "height: #{@height}"
  out << "data_size: #{data_size}"
  out
end

#interframe? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/flv/video_tag.rb', line 67

def interframe?
  frame_type == INTERFRAME || frame_type == DISPOSABLEINTERFRAME
end

#keyframe? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/flv/video_tag.rb', line 63

def keyframe?
  frame_type == KEYFRAME
end

#name ⇒ Object 



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# File 'lib/flv/video_tag.rb', line 50

def name
  case frame_type
  when KEYFRAME
    'Video Tag (Keyframe)'
  when INTERFRAME
    'Video Tag (Interframe)'
  when DISPOSABLEINTERFRAME
    'Video Tag (disposable Interframe)'
  else
    'Video Tag'
  end
end

#read_header ⇒ Object 



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# File 'lib/flv/video_tag.rb', line 71

def read_header
  data_stream = AMFStringBuffer.new(@data)

  # the sequence is swaped in the swf-file-format description
  # frame_type <-> codec_id (description: 1. codec_id, 2. frame_type)
  codec_id_and_frame_type = data_stream.read__UI8
  @frame_type = codec_id_and_frame_type >> 4
  @codec_id = codec_id_and_frame_type & 0xf

  bit_sequence = data_stream.read(9).unpack('B72').to_s
  
  if @codec_id == H263VIDEOPACKET
    @width, @height = case bit2uint bit_sequence[30,3]
    when 0
      [bit2uint(bit_sequence[33,8]), bit2uint(bit_sequence[41,8])]
    when 1
      [bit2uint(bit_sequence[33,16]), bit2uint(bit_sequence[49,16])]
    when 2
      [352, 288]
    when 3
      [176, 144]
    when 4
      [128, 96]
    when 5
      [320, 240]
    when 6
      [160, 120]
    end
  elsif @codec_id == SCREENVIDEOPACKET
    @width, @height = bit2uint(bit_sequence[4,12]), bit2uint(bit_sequence[16,12])
  end
end