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The Truth About High Bitrate Lossy Compression Part 3

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The Truth About High Bitrate Lossy Compression Part 3

BITRATE

For most users of the MP3 format, the problem of high quality sound is usually phrased as follows: “256 or 320? Or maybe try VBR?”

Bitrate

And this question haunts them day after day. Not all recordings sound good at 256; there is a strong audible and visible (measured) loss in the high frequency range. When using VBR mode (the so-called variable bit rate stream), it often happens that music sounds better by ear than 256, but this should not be taken as a general rule of thumb. Encode low-value or poor-quality records – you can’t go wrong. I have selected the VBR parameters to get the highest quality for VBR.

For the commercial LQT format, there is only one encoder proprietary to the authors: Liquifier Pro. We push them. Note that the LQT format is originally based on VBR encoding, so there are simply multiple modes for it, such as “bad”, “good”, and “excellent”. Naturally, for our tests we took the “excellent” (audiophile) mode, which results in a stream of 192 to 256, most of the time 200-220 kbps. Let me remind you that the LQT format is based on the MPEG-2 AAC family of algorithms. Also, this is the highest quality AAC implementation to date (tested on analogs).

The OGG format is a relative of the MP3 format, but it contains a different psychoacoustic model and some technical innovations that MP3 does not have. For starters, OGG initially only supports VBR mode. The user sets the approximate bit rate and the encoder tries to compress as closely as possible. The range of variation is extremely wide: 8 to 512 kbps, and it is much more discreet than MP3. The top bar is up to 512 kbit / s, whereas nowadays MP3 encoders really only “pull” up to 320. You may ask “is it possible that even 320 is not enough?” Yes, it happens, but rarely.

Roxette samples
Well, we come to the most interesting part. Let’s start with my auditory sensations.

For MP3 in a 256 kbps stream, noise disturbances at high frequencies are clearly audible. Not only is a considerable part of them absent from the sound, but strong distortion, wheezing, clanging and other “charms” are also mixed in. This is a sign that 256 is clearly not enough, therefore you need to test higher. Let’s take a 320 compressed sample. The sound has changed significantly, this is a completely different matter: the upper part is in place, no differences by ear were found. For the purity of the experiment, let’s see what happens in floating flow mode. We obtain an average bit rate of 290 kbit / s, of which the conclusion suggests that 256 for the sample under study will not be enough. In fact, a sample encoded in VBR mode sounds a little better than 256, but it clearly falls short of 320. In the case of MP3, for high-quality compression, only encoding in 320 kbps mode is adequate, ie , to the maximum of opportunities.

Let’s take OGG as “modified MP3”. There are five approximate bit rates for the encoder: 128, 160, 192, 256 and 350. Well, let’s try 192 and 256. We will not take 350 bit rates, because we already know that MP3 at 320 kbps clearly transmits excellent quality, it seems that better not necessary. For 192 mode, we get an average stream of 226, and for 256 mode, up to 315 kbps. So far the precision. Such a large deviation from the reference point is a signal for sound material that is very difficult to encode; with a sample with a simpler density, the precision will be higher. To be honest, I tried to evaluate 320 MP3 and 315 OGG for a long time and came to the conclusion that they both sound almost identical to the original sound. But they are based on different psychoacoustic models and their sound coloration is different. Personally, I liked the MP3 a bit more. But, this is really a controversial issue; after all, the OGG encoder is just a beta version. When there is a release, I think it should surpass MP3 in quality. Comparing them separately to the original, I was inclined to believe that the OGG has an even closer sound to the original, but there is something wrong with the high frequencies of this encoder. Because of this, MP3 sounds a bit better. I don’t think it is necessary to say that in 350 mode (average bitrate was 365) OGG “perfectly” repeats the original.

Now we are talking about the little-known but widely advertised format as the “highest quality”: the LQT format. And most importantly, it sounds great overall, however after listening to it, I realized that I didn’t like its sound. It doesn’t distort high frequencies, like MP3 256 kbps, but it smears the sound and smears a lot. Loud sounds fade over time.

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The Truth About High Bitrate Lossy Compression Part 2

The Truth About High Bitrate Lossy Compression Part 2

Bitrate

I decided to “drop” the three specified formats to get the highest quality sound with the minimum file size.

audio bitrate

For the test, we selected several samples (here a sample is a small fragment cut from a PCM file) from two types of compositions. The first is a very dense and loud sound with amplitude normalization (compacting the sound “vertically” to fit 16-bit from a 24-bit master) and compression of the dynamic range (so that the sound of all instruments is always strong). As the first type (as in my previous tests), the composition Crush On You from the album Have A Nice Day by Roxette was chosen, three samples of 15-20 seconds each of different parts of the composition were examined. The second sample is clean and transparent (acoustic or light orchestral arrangement).

Why these particular records? Roxette samples have very strong dynamic compression (the amplitude value is very often equal to the maximum (which is bad) and leads to overload of the playback equipment and strong distortions).

Roxette sample
In such samples, the encoders have to work in extreme mode, so any distortion becomes easily audible. encoding distortions add to the existing intrinsic distortions of the original. You ask “why then take a sample as a test?” It is necessary and how. The vast majority of albums released today are recorded this way. Therefore, the encoder must adequately accept clipping sound.

With Klaiderman’s samples, the situation is diametrically opposite. The original analog recording after a very high quality digital remastering was recorded to CD and without dynamic compression.

Clayderman sample
Great sound, very nice and smooth highs. We will pay special attention to them during the analysis, we will try to preserve them. But it is these frequencies that will be the most difficult for encoders to transmit.

the truth about high bitrate lossy compression

the truth about high bitrate lossy compression

bitrate lossy

Preface

bitrate lossy

In the understanding of most people, the word music lover is most often associated with a person who not only loves and collects music, but also appreciates high-quality music, and not only in artistic and aesthetic terms. but also the quality of the recording. of the phonogram itself. Think, a few years ago, an audio CD was considered the standard of music quality, but a computer, even in dreams, could not compete with the quality of a CD. However, time is a great joker and he often likes to turn things upside down. It would seem that quite a long time passed, one or two years and … that’s it, the CD on the PC went into the background. Don’t ask “why?”, You know the answer to this question yourself. Everything is to blame for the revolution in the world of sound on a computer: audio compression (hereinafter referred to as audiolo compression which means lossy compression to reduce the size of the audio file), which made it possible to store music on the hard drive, lots of music! In addition, it was possible to exchange it over the Internet. New sound cards have been released, capable of squeezing almost studio quality out of a piece of hardware that seems useless in terms of music. Today, even having a computer that is not very smart in performance, having bought a Creative SoundBlaster Live! And remembering that since the Soviet times there is a good amplifier and good acoustics, you will get nothing but a high-quality music center, the sound of which is inferior only to very expensive audio equipment (mid-range or even high-fidelity hi-fi). ). Add to this the general availability of music files and you know you have the power at your fingertips. And then there is a revolution, and you understand that a compact disc is no longer so convenient, you are fascinated by something completely different: the magic signs of the “MP3”. He cannot eat or sleep; faces the seemingly insoluble question of the “chicken and egg”: how to “squeeze” and, more importantly, how to “squeeze” …

This is where I will help you. This article is the beginning of my new series of informational materials on music on the computer. For over a year maintaining an extensive database of MP3 files, I have accumulated a great deal of research on audio compression. It is these studies that I will try to share with you. Several respected authors have written many articles on audio compression, so I will try not to write what I can easily find in other sources of information. I would like to express my position on the subject under discussion simply and clearly. We will not consider audio compression to be as compact a tool as possible put audio information on your hard drive (so that you can record so many hours of music there). Yes, compression allows you to record music more compactly, but my goal is to minimize quality loss by converting “pure” audio to compressed. That is why only high bitrates and encoders that compress qualitatively are considered in these modes. So it is much more convenient to work with compressed audio – instant access to any track from any album, convenient software for playback. And, of course, the financial issue has not been forgotten either.

Of the audio compression formats that exist today, three deserve attention, in my opinion: MP3 (or MPEG-1 Audio Layer III), LQT (as representative of the MPEG-2 AAC / MPEG-4 family) and the completely new OGG format (Ogg Vorbis) developed by a group of enthusiasts:

MP3 is by far the most widely used of these (mainly because it is free). Let me remind you that it was thanks to the MP3 format that the victorious procession of compressed audio took place. However, as is often the case with pioneers, little by little it is losing ground and giving way to new and better formats.
The second format, LQT, is a representative of a new direction of audio coding algorithms, a representative of the AAC family. This is a fairly high quality, but commercial and highly classified format.
OGG became widely known to the public this summer and is currently developing rapidly, soon (with the release of the Encoder and Decoder) it should beat MP3 with better sound quality with smaller file size.
I will not give a detailed description of technologies and formats here, you can easily find them yourself. There will only be facts, conclusions and recommendations. I plan to present my research separately for each format in separate articles.

The higher the bit rate, the better the track?

The higher the bit rate, the better the track?

bit rate

This is not always the case.

bit rate

For starters, let me remind you what bitrate t (bitrate, instead of bitraid). In fact, this is the data rate in kilobits per second during playback. That is, if we take the size of the track in kilobits and divide it by its duration in seconds, we get its bit rate, the call. File-based bitrate (FBR), usually not too different from the bitrate of the audio stream (the reason for the differences is the presence of metadata on the track: tags, “embedded” images, etc.) .

Now let’s take an example: the uncompressed PCM audio bit rate recorded on a normal audio CD is calculated as follows: 2 (channels) × 16 (bits per sample) × 44100 (samples per second) = 1411200 (bps ) = 1411.2 kbps. .. Now let’s take and compress the track with any lossless codec (“lossless” – “lossless”, that is, one that does not lead to information loss), for example, the FLAC codec. As a result, we will get a lower bit rate than the original, but the quality will remain unchanged; here is your first rebuttal.

Something else is worth adding here. The lossless compression output bitrate can be very different (but is generally lower than uncompressed audio); It depends on the complexity of the compressed signal, or rather on data redundancy. So simpler signals will compress better (ie we have smaller file size for the same duration => lower bitrate), and more complex signals will be worse. That’s why lossless classical music has a lower bitrate than, say, rock. But it must be emphasized that the bit rate here is in no way an indicator of the quality of the sound material.

Now let’s talk about lossy compression. First of all, you need to understand that there are many different encoders and formats, and even within the same format, the encoding quality for different encoders can differ (for example, QuickTime AAC encodes much better than outdated FAAC), not to mention the superiority of modern formats (OGG Vorbis, AAC, Opus) on MP3. Simply put, from two identical tracks encoded by different encoders with the same bit rate, some will sound better and some will sound worse.

Also, there is upconversion. That is, you can take a track in MP3 format with 96 kbps bit rate and convert it to 320 kbps MP3. Not only will the quality not improve (after all, data lost during the previous 96kbps encoding cannot be returned), it will even get worse. It is worth noting that at each lossy encoding stage (at any bit rate and any encoder) a certain amount of distortion is introduced into the audio.

And even more. There is one more nuance. If, say, the bit rate of an audio stream is 320 kbps, this does not mean that the 320 kbps was spent encoding that very second. This is typical for constant bit rate encoding and for those cases where a person, hoping for maximum quality, forces a constant bit rate too high (for example, setting CBR to 512 kbps for Nero AAC ). As you know, the number of bits assigned to a particular frame is regulated by the psychoacoustic model. But in case the allocated amount is much lower than the set bitrate, even the bit deposit is not saved (for terms see the article “What is CBR, ABR, VBR?”) – as a result, we get useless “zero bits” that simply “wrap up” the frame size to the desired one (that is, increase the size of the stream to the specified size). By the way, this is easy to check: compress the resulting file with a filing cabinet (preferably 7z) and look at the compression ratio – the more, the more zero bits (as they lead to redundancy), the more space wasted.

Bit rate as a characteristic of digital video and audio

Bit rate as a characteristic of digital video and audio

bit rate

Concept

bit rate

Bitrate: literally, the information bit rate. It is common to use the bit rate when measuring the effective information transmission rate through the channel, that is, the “payload” transmission rate (in addition to that, the channel can transmit service information, for example symbols start and stop for asynchronous transmission or control symbols for redundant coding). The baud rate, which takes into account the total bandwidth of the channel, is measured in baud.

Bit rate is the number of units of information required to store (transmit) one second of a stream of data (generally audio and video files). It is generally measured in ‘kbps’, kilobits per second.

The term bit rate is used in two basic meanings
: channel or device characteristic: the maximum number of bits that can be transmitted per unit of time.
– The amount of data stream transmitted in real time (the minimum channel size that this stream can pass through without delay).
– A special case is the compressed video or audio bit rate.
Bit rate is expressed in bits per second (bit / s, bps), as well as values derived with the prefixes kilo, mega, etc.

The term bitrate (along with subjective quality criteria) is often used as a characteristic to evaluate the performance of lossy compression algorithms.

Bitrate characterizes both the density of the information package and its quality. For example, out of two MP3 files compressed with different bit rates, a file with a higher bit rate will have higher sound quality (close to the original). At the same time, a file of a different format, with the same bit rate, can offer both better and worse sound quality.

On audio CDs, information is losslessly encoded at a constant 1407 kbps bit rate.

The MP3 format allows encoding audio information with constant or variable bitrate from 32 to 320 kbps, that is, they provide five times the compression compared to CD.

Bitrate and its calculation Bit rate (bit rate) Part 3

Bitrate and its calculation Bit rate (bit rate) Part 3

bit rate

coding.

bit rate

Codecs and Media Containers

Since 2014, the most common high definition video format is HD (Full HD), with a screen resolution of 1920 x 1080 pixels and a screen aspect ratio of 16 x 9. (This format is compatible with most modern LCD and plasma televisions, but not all are capable of providing a high quality picture.
The fact is that most of these televisions have a lower screen resolution than is necessary for viewing in Full HD, for example 1280×720. The HD format has varieties: 1080i and 1080p. As with other formats, the letters i and p represent progressively scanned or interlaced images.

But, unlike the usual PAL and NTSC formats, here with interlaced scanning the frame rate is 60 and with progressive scanning 50 frames per second. This is a standard, you can stick to it, but you can work around it too. The fact is that today a full HD format can only be played on a computer, there are no special devices (players) to watch it (HD DVD (gradually dying) and Blu-Ray disc players do not provide Full HD quality, but more on that later), therefore full compliance with the rules is no longer as important. The next most common high definition video quality and format is HDV, with a screen resolution of 1440 x 1080, but also with a 16×9 aspect ratio. This ratio is achieved by “stretching the pixels” horizontally, from 1440 to 1920. Therefore, for a Full HDV display, a FullHD television with a screen resolution of 1920×1080 is also required. Of course, the video quality in HDV format is lower than HD, but still, HDV format is quite common among users. The reason is that the HDV format was invented before HD, and even before the latter came out, a lot of video equipment was developed and released that only supports 1440×1080. High definition movies, generally recorded on HD DVD and Blu-Ray discs, also have an HDV resolution of 1440 x 1080. Even before the advent of HDV and HD, the 720p “high definition” format appeared. The resolution is 1280×720, the aspect ratio is 16×9. It is essentially a transitional format, from standard PAL to HDV and HD. The world’s first “high definition” hobby camcorder produced by JVC recorded at 720p. Even earlier, the PAL television format appeared in 720×576 resolution with 50 Hz interlaced scan. Now, this format is used in digital and satellite television (not HD). Now (2014-2017) I use mp4 format: mp4 – Full HD – 1920 x 1280, 16×9 variable bit rate 10 – 15 mbps for home viewing on 64 inch Full HD TV, this is enough. mp4 – HD – 1280 x 720, 16×9, variable bit rate 4-6 mbps. – if you need to save disk space, or if quality doesn’t really matter (or if you need to speed up rendering).
Источник: https://vseprost.ru/vybor-bitrejta-dlya-zapisi-multimedia.html

Bitrate and its calculation Bit rate (bit rate) Part 2

Bitrate and its calculation Bit rate (bit rate) Part 2

bit rate

Let’s go back to the DVD story for a moment.

bit rate

When the first analog-to-digital converters appeared in capture card form, it was claimed that 60 minutes of video could be put on a DVD-R with no loss of quality. In the claimed presentation data of the DVD format, the maximum bit rate of the multiplexed stream is 9.8 Mbit / s. When DVD recorders appeared that were capable of digitizing an analog signal in high quality, it was said that the recorder could fit up to 125 minutes on a disc without losing quality and up to 90 minutes if you wanted to save sound in PCM format.

We test, we verify, we write from both disk and videotapes; there is no visual difference even during pauses and in frame by frame mode (if the recorder is good). The bit rate that the recorders give to the output of the digitized image is 9000 Kbps and sometimes a little more. Why is the math not the same as the DVD burner result?

Probably because we do the calculation for a constant bit rate, and the recorders can already digitize video with a variable bit rate and have appropriate compression algorithms. By setting the upper limit of the bit rate at 9000 Kbps, you can achieve a good picture in video segments with dynamic actions, while in other parts of the same video the value of the bit rate can reach 2000 Kbps. noticed that when you record a video or a photo with a digital camera, the files have different sizes? Once the initial parameter is set, the codec itself chooses the value of the bit rate. Optimal bit rate for DVD video Considering the fact that up to 120 minutes of video can be recorded on DVD-R without quality loss, we ask ourselves: how to do this? Let’s consider 2 ways: 1. If you are using a DVD burner, set it to “lossless quality” mode and set to record. If your video is 60 minutes long, the recorder will not stretch it by 4. 36GB and it will only take up half the free space. 2. If you use a capture card or TV tuner, first capture as described here and then compress the resulting file with a quality program with modern codecs and multiple passes (at least the same Freemake Video Converter) at the speed of dvd5 for 120 minutes (don’t forget the menu). Consider an option when your video is short and you are not going to burn it to DVD-ROM or if you want to burn multiple MPEG-2 files to disc at once without losing quality. Below is a table calculated mathematically on the basis that you can fit 120 minutes of video on 4464MB of disk space (no menus). There are a few things to keep in mind: The table is written for MPEG-2 files. The table is not written for previously compressed videos. These values do not include a menu. Using different programs, you can get different results. The values in the table may vary depending on the content of the video. If the program has a bit rate option then you need to set “VBR” (variable). The values in the table are based on “lossless compression”. In this article, “lossless compression” refers to the viewing experience. In fact, in the analytical version, the word “compression” already denotes a loss of quality.
Источник: https://vseprost.ru/vybor-bitrejta-dlya-zapisi-multimedia.html

Bitrate and its calculation Bit rate (bit rate)

Bitrate and its calculation Bit rate (bit rate)

bit rate

Flow rate data per unit of time.

bit rate

Information flow is normally measured in bits and transit time in seconds (bit / s, bps). There are other quantities derived with the prefixes kilo- and mega- (kbit / s, kbit / s, kbps, Mbit / s, Mbps, Mbps). Bit rate is one of the main parameters of a video. Its value affects the size and quality of the video file. The bit rate is directly proportional to the quality and size of the file. The higher the bit rate, the better its quality and the larger the file size. Two types of speed must be distinguished: maximum bit rate: the maximum number of bits that can pass per unit of time, and bit rate: the bandwidth of the channel without delay.

Data stream compression modes

Constant Bit Rate Constant Bit Rate (CBR) is the encoding of the data stream, specified by the user and has a constant value throughout the length of the file. This mode improves compatibility and the ability to calculate more accurately, but can increase the size of the output file. Do not use this mode for dynamic scenes (sports programs, action movies, etc.) and when objects are moving in different directions. Variable Bit Rate (VBR) Variable Bit Rate is a mode in which the codec determines the amount of information stream transmitted based on the complexity of a given file segment. This mode produces the best quality in an optimal size and prevents flickering. The disadvantages of this method include only the unpredictability of the output file size and the possibility of incompatibility. Variable bit rate is actively used for burning Blu-Ray and DVD discs, where there is no limitation on the size of the file as such. Average Bit Rate (ABR) Average Bit Rate is a combination of variable and constant bit rates set by the user. Unlike variable bitrate, the data stream varies within strict limits and does not reach the minimum and maximum values. This allows you to predict the output file size much more accurately than VBR and improve video quality in fast-moving video scenes. The method was applied in the network. This mode is sometimes used to compress audio.

Bitrate calculation

Having mastered what the bit rate is and having disassembled the compression modes of the flow of information, we can proceed to the independent calculation of the bit rate. Let’s establish the conditions of the problem: video: home video 120 minutes long sound: present; menu: necessary; DVD-R Media (DVD + R) 4.36 GB; Output format: DVD (MPEG-2) DVD-R size: 4.36GB = 4464MB. Size is critical, so we will be calculating from 4300MB for several reasons: 1. Bitrate cannot be accurately calculated and the file may be larger than planned. All full disk space sometimes leads to improper disk startup. 3. Many programs are recoding based on this value. We subtract another 300MB for the menu and the audio track (if your sound is not in PCM format, whose bit rate is much higher, and if you don’t plan to create multiple audio tracks) and we get 4000MB. 4000: (120 * 60) = 0.556 Mbps = 0.556 * 8 = 4.444 Mbps = 4.444 * 1024 = 4551 Kbps. For a high-quality DVD-Rip, this value is ideal, but for MPEG-2 it is barely supportable. The fact is, different video formats need different bitrate values for an acceptable picture. You can try to play this video and if there are dynamic moments, you will see artifacts in the shape of squares in the video. It follows from this that you need to reduce the length of the file to about 60 minutes or look for other compression methods.

But what role does the bit rate play?

This term is known primarily for describing the quality of lossy compressed audio (eg MP3). Unfortunately, this makes it even more difficult than with channel-separated compression, the bit rate is split between the two channels: stereo MP3 (not to be confused with dual channel) with a 320 kBit / sec bit rate. uses only 160 kBit / sec per channel.

Bit Rate

Or different bit rates per channel: set stereo (mono signal calculated with additional stereo information), on the other hand, it works with volume differences between the two channels and therefore can use the bit rate much more efficiently .

Bitrate

DAC, bit rate

What exactly is the obviously so essential bit rate? For a CD based on the Red Book standard, the bit rate is calculated as follows: 2 channels * 44,100 Hz sample rate * 16 bit depth per sample results in 1,411,200 bits / sec., That is, 1.4112 Mbit / sec. Bit rate. Obviously, this is considerably more than what compressed formats (should) provide. You can see how the compression processes work: last but not least, they more or less cleverly reduce the bit depth per sample at a given sample rate of 44.1 kHz, for example. The amount of data decreases, and that is exactly the goal of every data compression: halving the bit rate means exactly halving the amount of data.

As an example, I have compared some common file formats for digital audio:

Format

Codec (s)

Multichannel

Sampling rate

Bit depth or resulting bit depth from bit rate

Compression
/
subject to acoustic losses

Wav

PCM et al.

yes

any

Optionally, depending on the codec, also lossless

AIFF

PCM et al.

Not

any

Not

FLAC

FLAC (Free Lossless Audio Codec)

yes

0.001 kHz-655.350 kHz

4, 8, 16, 20, 24, 32

without losses

Apple loses
less
MP4

ALAC (Apple Lossless Audio Codec)

yes

0.001 kHz-384,000 kHz

16, 20, 24, 32

without losses

MP3

MPEG I Layer 3 in various incarnations
as B. LAME

Not

8-48 kHz

8-320 kBit / sec. CBR / VBR or 640 CBR for free MP3 format

with mandatory loss

Most readers will know that lossy compression is often based on psychoacoustic models or natural limitations of human hearing: what humans cannot (should) hear is not stored in the musical signal and is irretrievably lost, apparently not. you need it. The most popular example of this is the old MP3 format already mentioned. For some audiophiles, lossy compression is by definition useless for serious music listening, regardless of whether or not they would notice the loss of compression. For others, the sound is 320 kBit / sec. MP3 encoded for pop music are identical to CDs, they are satisfied.

DAC bit rate

Lossless compression, on the other hand, has become increasingly popular since Internet bandwidths and storage capacities have steadily increased. An example is the FLAC format, which fortunately is also “open source”, which means that it can be used freely and even changed in terms of the program. Meanwhile, most of the time it is directly compatible with proprietary audio hardware, so FLAC files can be played without the help of a computer, and in some cases even created (ripped CDs). As the table above shows, FLAC supports very high sample rates and bit depths, as well as multi-channel sound.

With FLAC, the audio signal is encoded based on computable fixed-point algorithms that conserve computational power, in which blocks are formed step by step and stereo separation is converted to mid-side separation and performed the remodeling of the signal with differential storage. No information is lost, it is stored more efficiently than, for example, on a CD; Depending on the complexity of the audio signal, compression rates of up to 30% can be achieved.

FLAC

It should be clear once again that FLAC or MP3 are file formats and therefore cannot be directly compared to the PCM of the Red Book encoding of a CD or DSD (see next section). Let’s leave it at that on the subject of data compression.

What does “bit rate” mean in a video?

When downloading videos from the Internet or copying videos from disc to your computer, you may have the option of choosing a different bitrate. Even DVDs have specific bit rates. As technology has advanced, video media are able to achieve higher quality, such as high definition DVD, and this is achieved by increasing the video bit rate.

Bitrate

Definition

Bit rate, sometimes referred to as “bit rate”, is the term used to define compression of audio, video, or other multimedia compression in terms of the amount of data, measured in bits, per unit of time in the printed material. Bit rate is the ratio of quality to time. Bit rate is also often measured in kilobits or megabits per second.

Bitrate

Sense

Videos with a higher bit rate will have a larger file size. For example, it will take longer to download or stream from the Internet and upload to a device or computer, and you can burn fewer videos to DVD. However, a higher bit rate usually indicates a higher quality. In this way, your video can be clearer and sharper. When browsing for video or importing it to computer from DVD or camera, choose the highest bit rate for higher quality. However, if space is your main concern, choose the lowest bitrate when downloading or compressing video files.

bit rate factors

Programs will have different bit rates depending on different factors. For example, the output material may have more depth and quality, thus producing a higher bit rate. High definition movies have a higher bit rate than standard definition, for example. Different types of video files have different bit rates and you can also choose different bit rates for the same file. For example, iTunes allows you to compress audio files with a bit rate greater than 128 kilobytes per second to save space on your iPod.

Standard bit rates

Most standard definition DVDs have a maximum bit rate of 9.8 megabits. High definition television has a bit rate range between eight and 15 megabits per second, while the standard for 720p high definition video is approximately 19 megabits per second. At the time of publication, Blu-Ray DVDs have the highest bit rate of all consumer videos with a maximum of 40 megabits per second. This makes the content of Blu-Ray DVDs more than four times that of standard DVDs.