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• Smart y coordinate to make vertical alignment for the text with typewriting effect

  31 août 2021, par Макс Шульдинер

  I'm doing animation for the typewriting effect. Here is my ffmpeg string :

  


  -i ffmpeg_inputs/output-onlinegiftools.gif  -vf "[in]drawtext=fonts/RobotoMono-Regular.ttf:text='h':fontcolor=orange:fontsize=35:x=(w-text_w)/2-200+0:y=h-th-400:enable='between(t,0.00, 7.80)', drawtext =fonts/RobotoMono-Regular.ttf:text = 'i':fontcolor=orange:fontsize=35:x=(w-text_w)/2-200+25:y=h-th-400:enable='between(t,0.80, 7.80)', drawtext =fonts/RobotoMono-Regular.ttf:text = 'g':fontcolor=orange:fontsize=35:x=(w-text_w)/2-200+75:y=h-th-400:enable='between(t,1.60, 7.80)', drawtext =fonts/RobotoMono-Regular.ttf:text = 'u':fontcolor=orange:fontsize=35:x=(w-text_w)/2-200+100:y=h-th-400:enable='between(t,2.40, 7.80)', drawtext =fonts/RobotoMono-Regular.ttf:text = 'y':fontcolor=orange:fontsize=35:x=(w-text_w)/2-200+125:y=h-th-400:enable='between(t,3.20, 7.80)', drawtext =fonts/RobotoMono-Regular.ttf:text = 's':fontcolor=orange:fontsize=35:x=(w-text_w)/2-200+150:y=h-th-400:enable='between(t,4.00, 7.80)'[out]" ffmpeg_outputs/test2.gif -y 


  


  Here is the results with different y values :

  


  

  


  

  


  As i understand, to make smooth sentence, for some letters i need top vertical alignment, and for others i need bottom vertical alignment. How can i make this "smart alignment", or the only one method is to hardcode y values for different letters ?

  


• dca : fix misaligned access in avpriv_dca_convert_bitstream

  13 janvier 2016, par Andreas Cadhalpun

  dca : fix misaligned access in avpriv_dca_convert_bitstream
  src and dst are only 8-bit-aligned, so accessing them as uint16_t causes
  
  SIGBUS crashes on architectures like sparc.
  This fixes ubsan runtime error : load of misaligned address for type
  
  ’const uint16_t’, which requires 2 byte alignment
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Signed-off-by : Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
  

  • [DH] libavcodec/dca.c

• avcodec/videotoolboxenc : Fix concurrent access to CVPixelBufferRef

  7 juillet 2024, par Zhao Zhili

  avcodec/videotoolboxenc : Fix concurrent access to CVPixelBufferRef
  For a frame comes from AV_HWDEVICE_TYPE_VIDEOTOOLBOX, it's
  
  CVPixelBufferRef is maintained by a pool. CVPixelBufferRef returned
  
  to the pool when frame buffer reference reached to zero. However,
  
  VTCompressionSessionEncodeFrame also hold a reference to the
  
  CVPixelBufferRef. So a new frame get from av_hwframe_get_buffer
  
  may access a CVPixelBufferRef which still used by the encoder.
  
  It's only after vtenc_output_callback that we can make sure
  
  CVPixelBufferRef has been released by the encoder.
  The issue can be tested with sample from trac #10884.
  
  ffmpeg -hwaccel videotoolbox \
  
  	-hwaccel_output_format videotoolbox_vld \
  
          -i input.mp4 \
  
  	-c:v hevc_videotoolbox \
  
  	-profile:v main \
  
          -b:v 3M \
  
          -vf scale_vt=w=iw/2:h=ih/2:color_matrix=bt709:color_primaries=bt709:color_transfer=bt709 \
  
          -c:a copy \
  
  	-tag:v hvc1 \
  
  	output.mp4
  Withtout the patch, there are some out of order images in output.mp4.
  Signed-off-by : Zhao Zhili <zhilizhao@tencent.com>
  

  • [DH] libavcodec/videotoolboxenc.c