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Multimedia Codecs Based on FFT and Compatible with the WiFI Communications
We have recently introduced new methods for the compression, the decompression and the transport of media (audio, image and video).
For more information, see at the following addresses:
Image and Video Compression
Long Distance Communications
We also reported that these methods are usable with the OFDM, the OFDMA and the SC-FDMA.
For more information, see at the following address:
Multimedia Codecs based on FFT and Usable with OFDM, OFDMA and SC-FDMA
This information is written for investors, developers and decision makers.
This article aims to show how these methods can be used to transmit lossless media data, including audio, over WiFI.
For more information on the WiFI communication protocols, see at the following address:
WiFI
In the previously cited papers, we reported how one could transform the streams resulting from Huffman compression (usually used as additional compression in the last step) and the natural RLE (Run Length Encoding) streams into two-plane FFT streams.
Briefly:
- For the Huffman streams, the least frequent points are mapped to the foreground points of the FFT encoder output, the number of successive repetitions up to a certain limit being contained in the phase, and the other points are mapped to the background of the FFT encoder.
Successive repetitions in the background are ignored. Finally, the signs of the phases in the background are alternated.
- For the RLE streams, the values to be repeated are matched to the magnitudes and the number of repetitions, up to a certain limit, to the phases.
We either transmit two UNB (Ultra Narrow Band) frames, or we completely generate or complete the background and transport the foreground points into the background bands.
Since the number of repetitions is in the phases, we are forced to consider two frames without phase (cosine amplitudes and sine amplitudes), in each frame we bring the points closer together to have a UNB frame and we store the displacement values in the new phases introduced.
In this document, in the first two examples, we will create these streams artificially, in order to reach longer distances and have lower energy consumption.
1) Example of sending a lossless audio signal, in WiFI and OFDM.
- Take a signal from the time domain (16 bits / 8 or 16 kHz, 16 bits / 44 or 48 kHz, 24 bits / 96 or 192 kHz, ... ).
- Make the signal redundant by using ADPCM compression or a variant. Next to each value, place the remainder to be added so that there is no loss.
- Part of the remainder will be part of the background, the other part will constitute the foreground.
- Use the Huffman stream method and OFDM.
- Transport the foreground into the background phases, to go further without PAPR problems.
- Note the possibility of optimizing for each frame the parameters (tree) of the Huffman compression and transporting them into the background phases.
- Also note a doubling of the frame buffer if we add the rest, but we can aim for longer distances in difficult areas where there is generally more space (5 and 6 GHz or more for example).
- For the voice signals or if losses are tolerated, we can not add the rest. The foreground is made up of the largest points.
2) Example of sending a lossless audio signal, in WiFI and UNB.
With the previous method, the signal is redundant, but is not directly very compressible by RLE.
We use delta-sigma modulation to have redundant sequences of 0, 1, 01 and 10 and we use the RLE compression.
Note that large amplitudes are characterized by a large redundancy of 0 or 1, and that small amplitudes are characterized by a redundancy of 01 or 10.
At the end, we end up with two UNB frames to send (frame with cosine amplitudes and frame with sine amplitudes).
We can therefore aim for longer distances in difficult areas (5 and 6 GHz or more for example).
With the RLE stream method:
- There is the possibility of sending the two UNB frames with two spatial flows.
- There is the possibility of using the visible light communication systems with OFDM.
- There is the possibility of using the optical communication systems with OFDM.
- One can consider the possibility to simplify or even eliminate the DAC / ADC (Digital-to-Analog Converter / Analog-to-Digital Converter).
3) Example of sending a media signal (audio, image or video) in WiFI, using UNB, OFDM or SC-FDMA, and several frequency bands (multi-bands).
- We take a frame of the signal in the time domain, we pass it to the frequency domain by performing an FFT, then we generate two planes.
- We transform the foreground into two UNB frames.
- We transform the background into an OFDM or SC-FDMA frame.
- We send the foreground in a band where the communications are easy, and duplicate frames in bands where the communications are more difficult.
- We send the background in bands where the communications are more difficult.
4) Example of sending images from a display screen in WiFI.
- We switch from RGB format to YUV or YCbCr format or equivalent.
- For each of the components, we generate residuals via algorithms already known, in particular in the JPEG-LS compression, for example using the MED (Median Edge Detection) or LOCO-I predictor.
- The color components (U and V, Cb and Cr, ...) are highly compressible via RLE. We use the RLE method.
- For the Y component (luminance), we use the Huffman method.
- We can transport the foreground points of the Y components into the background phases.
- For the color components, one can use the pure RLE compression to have a field resembling a foreground, but composed only of amplitudes and repetition numbers, and transport these components into the background phases of the Y components.
For more information on the MED predictor, see at the following address:
Lossless JPEG
5) Example of sending a multichannel audio signal in WiFI.
- We create two groups of channels: a primary group and a secondary group.
- We put one or more channels in the primary group, the rest in the secondary group.
- Each channel of the secondary group is associated with a channel of the primary group.
- With a channel of the primary group, we generate residuals as in the first example and we use the Huffman stream method.
- With a channel of the secondary group, we generate residuals by subtracting amplitudes between the secondary channel and its associated primary channel, and we use the RLE stream method.
- We can transport the foreground points of a channel of the primary group into the background phases.
- We can transport the RLE streams of the secondary channels into the background phases of the associated primary channel.
For more information, see at the following addresses:
Image and Video Compression
Long Distance Communications
We also reported that these methods are usable with the OFDM, the OFDMA and the SC-FDMA.
For more information, see at the following address:
Multimedia Codecs based on FFT and Usable with OFDM, OFDMA and SC-FDMA
This information is written for investors, developers and decision makers.
This article aims to show how these methods can be used to transmit lossless media data, including audio, over WiFI.
For more information on the WiFI communication protocols, see at the following address:
WiFI
In the previously cited papers, we reported how one could transform the streams resulting from Huffman compression (usually used as additional compression in the last step) and the natural RLE (Run Length Encoding) streams into two-plane FFT streams.
Briefly:
- For the Huffman streams, the least frequent points are mapped to the foreground points of the FFT encoder output, the number of successive repetitions up to a certain limit being contained in the phase, and the other points are mapped to the background of the FFT encoder.
Successive repetitions in the background are ignored. Finally, the signs of the phases in the background are alternated.
- For the RLE streams, the values to be repeated are matched to the magnitudes and the number of repetitions, up to a certain limit, to the phases.
We either transmit two UNB (Ultra Narrow Band) frames, or we completely generate or complete the background and transport the foreground points into the background bands.
Since the number of repetitions is in the phases, we are forced to consider two frames without phase (cosine amplitudes and sine amplitudes), in each frame we bring the points closer together to have a UNB frame and we store the displacement values in the new phases introduced.
In this document, in the first two examples, we will create these streams artificially, in order to reach longer distances and have lower energy consumption.
1) Example of sending a lossless audio signal, in WiFI and OFDM.
- Take a signal from the time domain (16 bits / 8 or 16 kHz, 16 bits / 44 or 48 kHz, 24 bits / 96 or 192 kHz, ... ).
- Make the signal redundant by using ADPCM compression or a variant. Next to each value, place the remainder to be added so that there is no loss.
- Part of the remainder will be part of the background, the other part will constitute the foreground.
- Use the Huffman stream method and OFDM.
- Transport the foreground into the background phases, to go further without PAPR problems.
- Note the possibility of optimizing for each frame the parameters (tree) of the Huffman compression and transporting them into the background phases.
- Also note a doubling of the frame buffer if we add the rest, but we can aim for longer distances in difficult areas where there is generally more space (5 and 6 GHz or more for example).
- For the voice signals or if losses are tolerated, we can not add the rest. The foreground is made up of the largest points.
2) Example of sending a lossless audio signal, in WiFI and UNB.
With the previous method, the signal is redundant, but is not directly very compressible by RLE.
We use delta-sigma modulation to have redundant sequences of 0, 1, 01 and 10 and we use the RLE compression.
Note that large amplitudes are characterized by a large redundancy of 0 or 1, and that small amplitudes are characterized by a redundancy of 01 or 10.
At the end, we end up with two UNB frames to send (frame with cosine amplitudes and frame with sine amplitudes).
We can therefore aim for longer distances in difficult areas (5 and 6 GHz or more for example).
With the RLE stream method:
- There is the possibility of sending the two UNB frames with two spatial flows.
- There is the possibility of using the visible light communication systems with OFDM.
- There is the possibility of using the optical communication systems with OFDM.
- One can consider the possibility to simplify or even eliminate the DAC / ADC (Digital-to-Analog Converter / Analog-to-Digital Converter).
3) Example of sending a media signal (audio, image or video) in WiFI, using UNB, OFDM or SC-FDMA, and several frequency bands (multi-bands).
- We take a frame of the signal in the time domain, we pass it to the frequency domain by performing an FFT, then we generate two planes.
- We transform the foreground into two UNB frames.
- We transform the background into an OFDM or SC-FDMA frame.
- We send the foreground in a band where the communications are easy, and duplicate frames in bands where the communications are more difficult.
- We send the background in bands where the communications are more difficult.
4) Example of sending images from a display screen in WiFI.
- We switch from RGB format to YUV or YCbCr format or equivalent.
- For each of the components, we generate residuals via algorithms already known, in particular in the JPEG-LS compression, for example using the MED (Median Edge Detection) or LOCO-I predictor.
- The color components (U and V, Cb and Cr, ...) are highly compressible via RLE. We use the RLE method.
- For the Y component (luminance), we use the Huffman method.
- We can transport the foreground points of the Y components into the background phases.
- For the color components, one can use the pure RLE compression to have a field resembling a foreground, but composed only of amplitudes and repetition numbers, and transport these components into the background phases of the Y components.
For more information on the MED predictor, see at the following address:
Lossless JPEG
5) Example of sending a multichannel audio signal in WiFI.
- We create two groups of channels: a primary group and a secondary group.
- We put one or more channels in the primary group, the rest in the secondary group.
- Each channel of the secondary group is associated with a channel of the primary group.
- With a channel of the primary group, we generate residuals as in the first example and we use the Huffman stream method.
- With a channel of the secondary group, we generate residuals by subtracting amplitudes between the secondary channel and its associated primary channel, and we use the RLE stream method.
- We can transport the foreground points of a channel of the primary group into the background phases.
- We can transport the RLE streams of the secondary channels into the background phases of the associated primary channel.
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