How Do I???...Help with Tech questions
Feb 20, 2013 0:07:51 GMT -5
Post by stardust on Feb 20, 2013 0:07:51 GMT -5
DancyGeorgia said
Scroll is your friend if you don't want to read about technical details! Audio file formats is a complex subject. Hopefully I kept it simple enough.
MP4 (Mpeg-4) is what is called a "container" format used heavily in internet streaming. Other examples of container formats are TS and MTS which are used in broadcasting. Files in container formats can contain "streams" of video data, audio data, and text data (e.g. subtitles for the video). It may even contain more than 1 audio stream. I have a London Day 3 video in TS format with 3 different audio streams to chose from. If I play the file in VLC Media Player, I can choose which of the 3 audio steams I want it to play with the video, just like one can choose a different language or subtitles on some videos.
A MP4 file can contain audio in different formats, with AAC being the most commonly used but MP3 also possible.
M4A audio files are just MP4 files with only an audio stream. It is still a container file in the same format as MP4.
MP3 files are audio only files. They are not container files. The audio in the MP3 file is "compressed", i.e., the original audio was run through a software program that makes the file smaller by throwing out some of the audio data in frequency regions that humans don't hear very well. It is a "lossy" compression format, meaning that you cannot recover the original audio signal for the MP3 file since some of the information was thrown out. For music, the sound quality of MP3 depends on the "bit-rate" used in the compression algorithm. Most music download sites use a bit-rate of 256 kbps (kilo-bits per second) which is a good compromise between audio quality and file size. MP3 files with a bit-rate of 320 kbps are even better, but they are larger in size.
AAC is an audio only file which uses a better "lossy" audio compression algorithm than MP3. So, if you compare a MP3 and AAC file with the same bit-rate, the AAC file will have a better audio quality. AAC is the default audio format for YouTube, iTunes, iPhone, iPad, etc.
FLAC is another audio only file which uses a "lossless" audio compression. No audio information is lost during the compression so that the original audio can be reconstructed from the compressed file. FLAC files have better audio quality than either MP3 or AAC files. But FLAC files are much larger than MP3 or AAC files. Audiophiles prefer music in FLAC files. VLC Media Play can play FLAC files. Windows Media Player can also play FLAC files IF you also install a FLAC codec (the software that can read and interpret the compressed format). Instructions are in the How To thread of ATop. ALL OF THE LONDON QAL CONCERTS ARE AVAILABLE IN FLAC FORMAT, SO IT IS WELL WORTH BEING ABLE TO PLAY FLAC FILES ON YOUR COMPUTER USING HEADPHONE - YOU WILL LOVE, LOVE, LOVE IT!!! Some audio receivers can also play FLAC files on your stereo system.
If you download a video from YouTube in SD (Standard Definition, 360p) format, the audio will have a bit rate around 96 kbps. However, if you download a video from YouTube in HD (High Definition, either 720p or 1080p) format, the audio will have a bit rate around 192 kbps. So, if you want to rip audio from a video you downloaded from YouTube, use the HD video if available. However, either way, the audio is of lower quality than what you typically download from itunes or Amazon. 192 kbps would be good quality for an audiobook but is medium-low quality for music. 96 kbps is really low quality for music.
Back to the files in question. The person may have recorded the audio with a video camera, but could not hold the camera up to get video because of security. In this case, it may have originally been in a MP4 format which contained AAC or MP3 audio, most likely AAC which was later converted to MP3.
The kai357 MP4 download contains AAC audio with a bit rate of 114 kbps and "nominal" (maximum) bit rate of 128 kbps. norbik131's MP3 download of Japan Day 1 is in 128 kbps. My guess is that the kai357 download may have a bit better audio quality than the norbik131 download. There is also a MP3 download from Sccorpiobert which is in 256 kbps. This is likely better quality than the other 2 formats, but that is difficult to determine without knowing how the person obtained/converted the audio. This audio is supposed to fit on a CD but is one big file.
Any questions?
There are different quality levels for both MP3s and MP4s. Some MP3 are relatively low quality to compress the file size and create a smaller file. Other MP3 are very high quality.
This is from a few sites.
MP3 is Audio
MP4 is Audio,video,text.
MP3 is an audio-specific format. The compression removes certain parts of sound that are outside the normal human hearing range so cannot be heard by the listener. It provides a representation of pulse-code modulation — encoded audio in much less space than straightforward methods, by using psychoacoustic models to discard components less audible to human hearing, and recording the remaining information in an efficient manner. Similar principles are used by JPEG, an image compression format.
MP4 It is most commonly used to store digital audio and digital video streams, especially those defined by MPEG, but can also be used to store other data such as subtitles and still images. Like most modern container formats, MPEG-4 Part 14 allows streaming over the Internet. The official filename extension for MPEG-4 Part 14 files is .mp4, thus the container format is often referred to simply as MP4.
More about MP3 en.wikipedia.org/wiki/MP3
More about MP4 en.wikipedia.org/wiki/MPEG-4
This is from a few sites.
MP3 is Audio
MP4 is Audio,video,text.
MP3 is an audio-specific format. The compression removes certain parts of sound that are outside the normal human hearing range so cannot be heard by the listener. It provides a representation of pulse-code modulation — encoded audio in much less space than straightforward methods, by using psychoacoustic models to discard components less audible to human hearing, and recording the remaining information in an efficient manner. Similar principles are used by JPEG, an image compression format.
MP4 It is most commonly used to store digital audio and digital video streams, especially those defined by MPEG, but can also be used to store other data such as subtitles and still images. Like most modern container formats, MPEG-4 Part 14 allows streaming over the Internet. The official filename extension for MPEG-4 Part 14 files is .mp4, thus the container format is often referred to simply as MP4.
More about MP3 en.wikipedia.org/wiki/MP3
More about MP4 en.wikipedia.org/wiki/MPEG-4
MP4 (Mpeg-4) is what is called a "container" format used heavily in internet streaming. Other examples of container formats are TS and MTS which are used in broadcasting. Files in container formats can contain "streams" of video data, audio data, and text data (e.g. subtitles for the video). It may even contain more than 1 audio stream. I have a London Day 3 video in TS format with 3 different audio streams to chose from. If I play the file in VLC Media Player, I can choose which of the 3 audio steams I want it to play with the video, just like one can choose a different language or subtitles on some videos.
A MP4 file can contain audio in different formats, with AAC being the most commonly used but MP3 also possible.
M4A audio files are just MP4 files with only an audio stream. It is still a container file in the same format as MP4.
MP3 files are audio only files. They are not container files. The audio in the MP3 file is "compressed", i.e., the original audio was run through a software program that makes the file smaller by throwing out some of the audio data in frequency regions that humans don't hear very well. It is a "lossy" compression format, meaning that you cannot recover the original audio signal for the MP3 file since some of the information was thrown out. For music, the sound quality of MP3 depends on the "bit-rate" used in the compression algorithm. Most music download sites use a bit-rate of 256 kbps (kilo-bits per second) which is a good compromise between audio quality and file size. MP3 files with a bit-rate of 320 kbps are even better, but they are larger in size.
AAC is an audio only file which uses a better "lossy" audio compression algorithm than MP3. So, if you compare a MP3 and AAC file with the same bit-rate, the AAC file will have a better audio quality. AAC is the default audio format for YouTube, iTunes, iPhone, iPad, etc.
FLAC is another audio only file which uses a "lossless" audio compression. No audio information is lost during the compression so that the original audio can be reconstructed from the compressed file. FLAC files have better audio quality than either MP3 or AAC files. But FLAC files are much larger than MP3 or AAC files. Audiophiles prefer music in FLAC files. VLC Media Play can play FLAC files. Windows Media Player can also play FLAC files IF you also install a FLAC codec (the software that can read and interpret the compressed format). Instructions are in the How To thread of ATop. ALL OF THE LONDON QAL CONCERTS ARE AVAILABLE IN FLAC FORMAT, SO IT IS WELL WORTH BEING ABLE TO PLAY FLAC FILES ON YOUR COMPUTER USING HEADPHONE - YOU WILL LOVE, LOVE, LOVE IT!!! Some audio receivers can also play FLAC files on your stereo system.
If you download a video from YouTube in SD (Standard Definition, 360p) format, the audio will have a bit rate around 96 kbps. However, if you download a video from YouTube in HD (High Definition, either 720p or 1080p) format, the audio will have a bit rate around 192 kbps. So, if you want to rip audio from a video you downloaded from YouTube, use the HD video if available. However, either way, the audio is of lower quality than what you typically download from itunes or Amazon. 192 kbps would be good quality for an audiobook but is medium-low quality for music. 96 kbps is really low quality for music.
Back to the files in question. The person may have recorded the audio with a video camera, but could not hold the camera up to get video because of security. In this case, it may have originally been in a MP4 format which contained AAC or MP3 audio, most likely AAC which was later converted to MP3.
The kai357 MP4 download contains AAC audio with a bit rate of 114 kbps and "nominal" (maximum) bit rate of 128 kbps. norbik131's MP3 download of Japan Day 1 is in 128 kbps. My guess is that the kai357 download may have a bit better audio quality than the norbik131 download. There is also a MP3 download from Sccorpiobert which is in 256 kbps. This is likely better quality than the other 2 formats, but that is difficult to determine without knowing how the person obtained/converted the audio. This audio is supposed to fit on a CD but is one big file.
Any questions?
