rajpurkar/squad huggingface dataset:
Title: MP3

The MPEG-1 standard does not include a precise specification for an MP3 encoder, but does provide example psychoacoustic models, rate loop, and the like in the non-normative part of the original standard. At present, these suggested implementations are quite dated. Implementers of the standard were supposed to devise their own algorithms suitable for removing parts of the information from the audio input. As a result, there are many different MP3 encoders available, each producing files of differing quality. Comparisons are widely available, so it is easy for a prospective user of an encoder to research the best choice. An encoder that is proficient at encoding at higher bit rates (such as LAME) is not necessarily as good at lower bit rates.

Question: Which standard does not include a specification for an MP3 encoder?
Answer: MPEG-1

Question: Example psychoacoustic models and rate loops can be foundin which part of the original standard?
Answer: non-normative

Question: What were implementers of the standard supposed to devise?
Answer: their own algorithms

Question: It is easy for a prospective user of an encoder to research the best choice because of what factor?
Answer: Comparisons are widely available

Question: An encoder that is proficient at encoding at higher bit rates might be worse at what?
Answer: lower bit rates
Title: MP3

During encoding, 576 time-domain samples are taken and are transformed to 576 frequency-domain samples.[clarification needed] If there is a transient, 192 samples are taken instead of 576. This is done to limit the temporal spread of quantization noise accompanying the transient. (See psychoacoustics.)

Question: How many domain samples are taken during encoding?
Answer: 576

Question: Domain samples are transformed into what?
Answer: frequency-domain samples

Question: When are 192 samples taken instead of 576?
Answer: there is a transient

Question: When 192 samples are taken instead of 576, it is done in an effort to limit what?
Answer: temporal spread

Question: What accompanies a transient?
Answer: quantization noise
Title: MP3

Due to the tree structure of the filter bank, pre-echo problems are made worse, as the combined impulse response of the two filter banks does not, and cannot, provide an optimum solution in time/frequency resolution. Additionally, the combining of the two filter banks' outputs creates aliasing problems that must be handled partially by the "aliasing compensation" stage; however, that creates excess energy to be coded in the frequency domain, thereby decreasing coding efficiency.[citation needed]

Question: What kind of structure does a filter bank have?
Answer: tree

Question: Due to a specific kind of structure, what kind of problems are made worse?
Answer: pre-echo problems

Question: What kind of resolution are the filter banks unable to provide an optimal solution for?
Answer: time/frequency

Question: Combining two filter banks' outputs creates what kind of problem?
Answer: aliasing

Question: The need to code excess energy in the frequency domain decreases what kind of efficiency?
Answer: coding
Title: MP3

Decoding, on the other hand, is carefully defined in the standard. Most decoders are "bitstream compliant", which means that the decompressed output that they produce from a given MP3 file will be the same, within a specified degree of rounding tolerance, as the output specified mathematically in the ISO/IEC high standard document (ISO/IEC 11172-3). Therefore, comparison of decoders is usually based on how computationally efficient they are (i.e., how much memory or CPU time they use in the decoding process).

Question: What is carefully defined in the standard?
Answer: Decoding

Question: What are most decoders?
Answer: bitstream compliant

Question: The ISO/IEC high standard document states that the decompressed output produced from a given MP3 file will be the same within what standards?
Answer: specified degree of rounding tolerance

Question: Decoders are usually compared by examining which factor?
Answer: computationally efficient

Question: The efficiency of decoders is examined by seeing how much memory and what other process they use in the decoding process?
Answer: CPU time
Title: MP3

Encoder / decoder overall delay is not defined, which means there is no official provision for gapless playback. However, some encoders such as LAME can attach additional metadata that will allow players that can handle it to deliver seamless playback.

Question: What is there no official provision for?
Answer: gapless playback

Question: What is an example of an encoder that can attach additional metadeta?
Answer: LAME

Question: Adding additional metadata allows players to handle gapless playback and deliver what?
Answer: seamless playback

Question: For encoders and decoders, what is not defined?
Answer: overall delay
Title: MP3

When performing lossy audio encoding, such as creating an MP3 file, there is a trade-off between the amount of space used and the sound quality of the result. Typically, the creator is allowed to set a bit rate, which specifies how many kilobits the file may use per second of audio. The higher the bit rate, the larger the compressed file will be, and, generally, the closer it will sound to the original file.

Question: A typical trade off when creating an MP3 file is between the amount of space used and what other factor?
Answer: sound quality of the result

Question: What would an example of lossy audio encoding be?
Answer: creating an MP3 file

Question: Who gets to set the bit rate for an MP3 file?
Answer: the creator

Question: What does the bit rate of the file actually mean?
Answer: how many kilobits the file may use per second of audio

Question: If the bit rate is higher, the size of the compressed file will be what?
Answer: larger
Title: MP3

With too low a bit rate, compression artifacts (i.e., sounds that were not present in the original recording) may be audible in the reproduction. Some audio is hard to compress because of its randomness and sharp attacks. When this type of audio is compressed, artifacts such as ringing or pre-echo are usually heard. A sample of applause compressed with a relatively low bit rate provides a good example of compression artifacts.

Question: If the bit rate is too low, what might be audible in the reproduction?
Answer: compression artifacts

Question: Sounds that were not in the original recording are referred to as what?
Answer: compression artifacts

Question: Randomness and sharp attacks are two reasons that may make it harder to to do what to an audio file?
Answer: compress

Question: Other than pre - echo, what is another example of what can happen when audio is compressed?
Answer: ringing

Question: What kind of sample can display a good example of compression artifacts?
Answer: A sample of applause
Title: MP3

Besides the bit rate of an encoded piece of audio, the quality of MP3 files also depends on the quality of the encoder itself, and the difficulty of the signal being encoded. As the MP3 standard allows quite a bit of freedom with encoding algorithms, different encoders may feature quite different quality, even with identical bit rates. As an example, in a public listening test featuring two different MP3 encoders at about 128 kbit/s, one scored 3.66 on a 1–5 scale, while the other scored only 2.22.

Question: Other than the bit rate and the difficulty of the signal, what can also affect the quality of an MP3 file?
Answer: quality of the encoder

Question: The MP3 standard allows encoders to have a lot of freedom with which aspect of encoding?
Answer: encoding algorithms

Question: As a result of the freedom, different encoders can result in different quality even if which aspect of the file is the same?
Answer: bit rates

Question: An example shown has a low range quality score of what value?
Answer: 2.22

Question: To compare qualities, sound files are evaluated on a scale that ranges from 1 to what?
Answer: 5
Title: MP3

The simplest type of MP3 file uses one bit rate for the entire file: this is known as Constant Bit Rate (CBR) encoding. Using a constant bit rate makes encoding simpler and faster. However, it is also possible to create files where the bit rate changes throughout the file. These are known as Variable Bit Rate (VBR) files. The idea behind this is that, in any piece of audio, some parts will be much easier to compress, such as silence or music containing only a few instruments, while others will be more difficult to compress. So, the overall quality of the file may be increased by using a lower bit rate for the less complex passages and a higher one for the more complex parts. With some encoders, it is possible to specify a given quality, and the encoder will vary the bit rate accordingly. Users who know a particular "quality setting" that is transparent to their ears can use this value when encoding all of their music, and generally speaking not need to worry about performing personal listening tests on each piece of music to determine the correct bit rate.

Question: How many bit rates does the simplest type of MP3 file use?
Answer: one

Question: What does CBR stand for?
Answer: Constant Bit Rate

Question: What does VBR stand for?
Answer: Variable Bit Rate

Question: Aside from silence, which sections of music highlight parts that are easier to compress?
Answer: music containing only a few instruments

Question: What value do users need to know when encoding their music to help avoid them having to do tests on each piece of music?
Answer: quality setting
Title: MP3

Perceived quality can be influenced by listening environment (ambient noise), listener attention, and listener training and in most cases by listener audio equipment (such as sound cards, speakers and headphones).

Question: A listening environment is also know by which term?
Answer: ambient noise

Question: Other than speakers and headphones, what other piece of equipment affects the listener's perceived quality?
Answer: sound cards

Question: Listening environment, listener attention, listener training and listener audio equipment can all affect what kind of quality?
Answer: Perceived quality
Title: MP3

A test given to new students by Stanford University Music Professor Jonathan Berger showed that student preference for MP3-quality music has risen each year. Berger said the students seem to prefer the 'sizzle' sounds that MP3s bring to music.

Question: Who gave students a test to determine their preferences?
Answer: Music Professor Jonathan Berger

Question: Where was a test performed to collect data on student preference for MP3 quality?
Answer: Stanford University

Question: Data showed that students' preference for MP3 quality music followed which trend?
Answer: risen each year

Question: What kind of sound did students seem to prefer?
Answer: sizzle
Title: MP3

An in-depth study of MP3 audio quality, sound artist and composer Ryan Maguire's project "The Ghost in the MP3" isolates the sounds lost during MP3 compression. In 2015, he released the track "moDernisT" (an anagram of "Tom's Diner"), composed exclusively from the sounds deleted during MP3 compression of the song "Tom's Diner", the track originally used in the formulation of the MP3 standard. A detailed account of the techniques used to isolate the sounds deleted during MP3 compression, along with the conceptual motivation for the project, was published in the 2014 Proceedings of the International Computer Music Conference.

Question: What is the name of the study done by composer Ryan Maguire?
Answer: The Ghost in the MP3

Question: What did the study aim to isolate?
Answer: sounds lost during MP3 compression

Question: What is the track "moDernisT" an anagram of?
Answer: Tom's Diner

Question: Where was an account of the study published?
Answer: International Computer Music Conference

Question: Which year was the study published?
Answer: 2014
Title: MP3

Several bit rates are specified in the MPEG-1 Audio Layer III standard: 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256 and 320 kbit/s, with available sampling frequencies of 32, 44.1 and 48 kHz. MPEG-2 Audio Layer III allows bit rates of 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 kbit/s with sampling frequencies of 16, 22.05 and 24 kHz. MPEG-2.5 Audio Layer III is restricted to bit rates of 8, 16, 24, 32, 40, 48, 56 and 64 kbit/s with sampling frequencies of 8, 11.025, and 12 kHz.[citation needed] Because of the Nyquist–Shannon sampling theorem, frequency reproduction is always strictly less than half of the sampling frequency, and imperfect filters requires a larger margin for error (noise level versus sharpness of filter), so 8 kHz sampling rate limits the maximum frequency to 4 kHz, while 48 kHz maximum sampling rate limits an MP3 to 24 kHz sound reproduction.

Question: What is the name of the sampling theorem?
Answer: Nyquist–Shannon

Question: In relation to the sampling frequency, the frequency reproduction is strictly how much less?
Answer: less than half

Question: Having an 8 kHz sampling rate would limit the maximum frequency to how much?
Answer: 4 kHz

Question: What kind of filter requires a larger margin for error?
Answer: imperfect filters

Question: A sound reproduction of 24 kHz would represent which value of a maximum sampling rate?
Answer: 48
Title: MP3

A sample rate of 44.1 kHz is almost always used, because this is also used for CD audio, the main source used for creating MP3 files. A greater variety of bit rates are used on the Internet. The rate of 128 kbit/s is commonly used, at a compression ratio of 11:1, offering adequate audio quality in a relatively small space. As Internet bandwidth availability and hard drive sizes have increased, higher bit rates up to 320 kbit/s are widespread.

Question: What sampling rate is used for CD audio?
Answer: 44.1 kHz

Question: What is the main source used for creating MP3 files?
Answer: CD audio

Question: Where can one find a greater variety of bit rates?
Answer: the Internet

Question: The common bit rate on the internet is 128 kbit/s using which compression ratio?
Answer: 11:1

Question: As technology advances, what is another higher bit rate that is beginning to spread?
Answer: 320 kbit/s
Title: MP3

Uncompressed audio as stored on an audio-CD has a bit rate of 1,411.2 kbit/s, (16 bit/sample × 44100 samples/second × 2 channels / 1000 bits/kilobit), so the bitrates 128, 160 and 192 kbit/s represent compression ratios of approximately 11:1, 9:1 and 7:1 respectively.

Question: What is stored on an audio-CD that has a bit rate of 1,411.2 kbit/s?
Answer: Uncompressed audio

Question: What does a bit rate of 128 represent in terms of compression ratio?
Answer: 11:1

Question: What would a bit rate of 160 correspond to in terms of compression ratio?
Answer: 9:1

Question: What would a bit rate of 192 kbit/s have for a compression ratio?
Answer: 7:1
Title: MP3

Non-standard bit rates up to 640 kbit/s can be achieved with the LAME encoder and the freeformat option, although few MP3 players can play those files. According to the ISO standard, decoders are only required to be able to decode streams up to 320 kbit/s.

Question: The LAME encoder allows bit rates that are what?
Answer: Non-standard

Question: Even though few MP3 players can play it, LAME also offers which option?
Answer: freeformat

Question: What is the highest bit rate the LAME encoder allows?
Answer: 640 kbit/s

Question: The ISO standard dictates that decoders only need to be able to decode streams that have how high of a bit rate?
Answer: 320
Title: MP3

Early MPEG Layer III encoders used what is now called Constant Bit Rate (CBR). The software was only able to use a uniform bitrate on all frames in an MP3 file. Later more sophisticated MP3 encoders were able to use the bit reservoir to target an average bit rate selecting the encoding rate for each frame based on the complexity of the sound in that portion of the recording.

Question: What does the term CBR mean?
Answer: Constant Bit Rate

Question: Which early MPEG layer used CBR?
Answer: Layer III

Question: The early software was restricted to which kind of bitrate?
Answer: uniform

Question: What did more sophisticated MP3 encoders use to target an average bit rate?
Answer: bit reservoir

Question: What did encoders base the encoding rate for each frame on?
Answer: the complexity of the sound
Title: MP3

A more sophisticated MP3 encoder can produce variable bitrate audio. MPEG audio may use bitrate switching on a per-frame basis, but only layer III decoders must support it. VBR is used when the goal is to achieve a fixed level of quality. The final file size of a VBR encoding is less predictable than with constant bitrate. Average bitrate is VBR implemented as a compromise between the two: the bitrate is allowed to vary for more consistent quality, but is controlled to remain near an average value chosen by the user, for predictable file sizes. Although an MP3 decoder must support VBR to be standards compliant, historically some decoders have bugs with VBR decoding, particularly before VBR encoders became widespread.

Question: What kind of audio can a sophisticated MP3 encoder produce?
Answer: variable bitrate audio

Question: Which type of decoder must support bitrate switching on a per-frame basis?
Answer: layer III

Question: What do encoders use when the goal is to achieve a fixed level of quality?
Answer: VBR

Question: Using VBR instead of a constant bit rate encoding makes which part of encoding less predictable?
Answer: final file size

Question: An average bit rate is used when who choses an average value for the encoder to use?
Answer: the user
Title: MP3

Layer III audio can also use a "bit reservoir", a partially full frame's ability to hold part of the next frame's audio data, allowing temporary changes in effective bitrate, even in a constant bitrate stream. Internal handling of the bit reservoir increases encoding delay.[citation needed]

Question: A partially full frame's ability to have part of the next frame's audio data is referred to as what?
Answer: bit reservoir

Question: What kind of audio is required to use a bit reservoir?
Answer: Layer III

Question: What is a possible result of handling the bit reservoir?
Answer: encoding delay

Question: A bit reservoir allows for what kind of changes in effective bit rate?
Answer: temporary

Question: A large benefit of a bit reservoir is that you can use it even while encoding what kind of stream?
Answer: constant bitrate
Title: MP3

There is no scale factor band 21 (sfb21) for frequencies above approx 16 kHz, forcing the encoder to choose between less accurate representation in band 21 or less efficient storage in all bands below band 21, the latter resulting in wasted bitrate in VBR encoding.

Question: What can scale factor band 21 be shortened to?
Answer: sfb21

Question: What is the maximum frequency that scale factor band 21 can go up to?
Answer: 16 kHz

Question: The encoder has to choose between less acurate representation in band 21 or which factor in all bands below band 21?
Answer: less efficient storage

Question: What does less efficient storage result in for VBR encoding?
Answer: wasted bitrate
Title: MP3

A "tag" in an audio file is a section of the file that contains metadata such as the title, artist, album, track number or other information about the file's contents. The MP3 standards do not define tag formats for MP3 files, nor is there a standard container format that would support metadata and obviate the need for tags.

Question: What is a section of a file that contains metadeta referred to as?
Answer: tag

Question: What else can metadeta contain other than the title, artist or track  number?
Answer: album

Question: What do MP3 standards not define?
Answer: tag formats for MP3 files

Question: What would be needed to support metadata and obviate the need for tags?
Answer: a standard container format
Title: MP3

However, several de facto standards for tag formats exist. As of 2010, the most widespread are ID3v1 and ID3v2, and the more recently introduced APEv2. These tags are normally embedded at the beginning or end of MP3 files, separate from the actual MP3 frame data. MP3 decoders either extract information from the tags, or just treat them as ignorable, non-MP3 junk data.

Question: Other than the ID3v1, which similar standard format for tag exists?
Answer: ID3v2

Question: What is the most recently introduced standard for tag formatting?
Answer: APEv2

Question: What is the second place in a file that tags are normally stored, with the first being at the beginning?
Answer: end

Question: What is important to note about where the tags are stored?
Answer: separate from the actual MP3 frame data

Question: If the MP3 decoders do not extract information from the tags, what do they do to them?
Answer: treat them as ignorable, non-MP3 junk data
Title: MP3

ReplayGain is a standard for measuring and storing the loudness of an MP3 file (audio normalization) in its metadata tag, enabling a ReplayGain-compliant player to automatically adjust the overall playback volume for each file. MP3Gain may be used to reversibly modify files based on ReplayGain measurements so that adjusted playback can be achieved on players without ReplayGain capability.

Question: What is the name given to the standard for measure and storing the loudness of an MP3 file?
Answer: ReplayGain

Question: What is measuring and storing loudness of an MP3 file also known as?
Answer: audio normalization

Question: What does the standard ReplayGain allow a player to automatically adjust?
Answer: the overall playback volume

Question: What program can be used to modify files based on ReplayGain measurements?
Answer: MP3Gain

Question: MP3Gain is important because it allows players without what capability to have adjusted playback?
Answer: ReplayGain capability
Title: MP3

The basic MP3 decoding and encoding technology is patent-free in the European Union, all patents having expired there. In the United States, the technology will be substantially patent-free on 31 December 2017 (see below). The majority of MP3 patents expired in the US between 2007 and 2015.

Question: Where is the basic MP3 decoding and technology patent free?
Answer: European Union

Question: What happened to the patents that caused them to be patent-free?
Answer: expired

Question: When will the technology be patent - free in the United States?
Answer: 31 December 2017

Question: Between which years did most of the MP3 patents in the US expire?
Answer: 2007 and 2015
Title: MP3

In the past, many organizations have claimed ownership of patents related to MP3 decoding or encoding. These claims led to a number of legal threats and actions from a variety of sources. As a result, uncertainty about which patents must be licensed in order to create MP3 products without committing patent infringement in countries that allow software patents was a common feature of the early stages of adoption of the technology.

Question: What has many organizations claiming ownership of patents related to aspects of MP3 led to?
Answer: legal threats

Question: Legal threats and confusion made it difficult to ensure what about patents regarding MP3 products?
Answer: which patents must be licensed

Question: What was the danger of not correctly patenting products?
Answer: patent infringement

Question: At what stage of the technology were these problems prevalent?
Answer: early stages