All posts by Mr Stratton

Computing teacher and a PT at Coltness High School.
3. Multimedia, Computing Higher

Digital Audio Convertors DAC

I’m publishing this way back in September, I am having a guess at the date we will be covering this topic.

Description of features of sound cards, including:

  • role of DAC

The DAC converts a stream of digital bits into an analogue signal. This signal is then changed into a sound wave by an amplifier and speakers.

The human ear is a complicated thing and as I said in class your hearing is diminishing with age. So is there a difference between 16 and 24 bit? Well probability not for me but your young ears might find the difference quite noticeable.

Revision

Easter School

Unfortunately I am not able to take part in Easter school this year. However, there are still 3 weeks left in the term and supported study operates on a Monday lunchtime and Wednesday after school. This would be more time than you would get with me at Easter school. Please make an effort to attend if you feel you need more help.

3. Multimedia, Computing Higher

Interlacing Bitmaps

Downloading large bitmap images from the Internet over a slow network connection can be frustrating, especially over a slow mobile connection. It might be that the image you are trying to view is not the correct one but you would have to wait for the full image to be displayed line by line before you are sure

However, with interlacing the image is downloaded by alternate lines. This results in a blurring then smoothing effect. Roughly the same amount of data is transmitted, just the order is changed.

3. Multimedia, Computing Higher

Work for Tuesday 11th March

Today you are going to investigate the different types of bitmap graphics file we will use during the course.  You must create a presentation which covers Bitmap,GIF,JPEG & PNG file formats. You can use your notes, the scholar website and other websites including this one to do your research. A clear example of each file type must be included in the presentation, this should show some advantage or disadvantage of the image format. Please use the point below to help you in your investigation.

Description of the storage of graphic data in compressed and uncompressed file formats, including simple description of the techniques used within each file for compression and data storage, including:

  • bitmap (indexed colour or CLUT), 24-bit bitmap and compressed bitmap (RLE),
  • GIF (animation, (non)-interlaced, LZW),
  • JPEG (description of factors involved),
  • PNG (CLUT or RGB, transparency, compressed)