bitstream or pcm

what is the difference between connecting a dvd player to amp, having the output mode of dvd player set to bitstream and pcm. how difference these setting will influence the output of sound.

Bitstream is digital output to the amp, it means either optical or coaxial output should be connected to the receiver. The digital to analog conversion will be done by the receiver.

PCM is analog output. Analog output should be connected to the receiver. For DTS etc, your player should have a dts decoder and the 5 channel output should be connected to the receiver's external decoder inputs.

Doors, you information is only partially correct. PCM is not analog, but digital. Let me explain.

There are lots of confusion between PCM/LPCM and bitstream. This confusion is there because the two refer to completely different things - one is a encoding and storage methodology, while the other is just a transport mechanism.

Pulse Code Modulation or PCM is a digital form of representing analog signals. PCM has two step process - one is called Modulation and other is called Demodulation. In Modulation, an analog signal is sampled at regular intervals and quantisized. For each sample, an available value is chosen using an advanced algorithm. This creates a fully discreet digital signal that can be easily stored and processed. In demodulation, the modulation process is reversed and a high frequency analog signal is created. This is them sent though a filter to remove, what we in audio call, jitter. Modulation is what we know as Analog-to-Digital conversion, and demodulation is what we call Digital-to-Analog conversion. Both your audio CD as well as your DVD store digital data that have been created using PCM.

For a long time, because of the small spaces available for storage (CD, DVD, etc) as well narrow bandwidths available for data transmission, digital data has been stored in lossy compressed form for both audio and video. Such compression always have some loss of data.

Using optical or co-axial connections, these compressed digital data is streamed across from one point to another. Since a bit is the most basic form of digital data, this way of transmission is called bitstreaming. Digital data is streamed using synchronous or asynchronous modes. In computer for example, TCP uses asynchronous mode for data transportation.

Most data streams are sent as packets or frames of data and contain the following information:

* header
* error check
* audio or video data
* ancillary data

The header of each packet contains general information such as the CODEC, sampling frequency, number of channels, CRC protection, etc. On the receiving side, the data is validated for accuracy, and once validated, the actual data is processed as needed.

Over the last few years two things have happened. Storage space has increased, and new transmission methodology have been discovered that have a much higher bandwidth. HDMI 1.3, for example, can carry data at a bandwidth of 340 MHz which equals to 10.2 giga bits per second. In addition HDMI also allows multiplexing of multi data streams over a single physical link. A 192 kHz sampling frequency equates to just 6.144 gigabits per second of transmission speeds.

Now suddenly you could store data with lossless compression, and also transmit multiple channels of data from one place to another at very high speed.

LPCM is a term that is loosely used for both encoding and storage, and of decoding and transmission of lossless video/audio data. LPCM sampling resolutions can go up to 24 bits per sample, while PCM's resolution is a max of 16 bits. LPCM is generally used in conjunction with WAV files in computers (also FLAC, AIFF etc), and with Blu-Ray, TrueHD, DTS-HD

PCM and bitstream is used in conjunction with traditional formats such as 2 channel stereo, Dolby Digital, DTS, etc.

The question is which one should I use?

If you are using coaxial or optical digital connection, you must use bitstream or what some players call RAW. Many DVD players will have PCM set as default. PCM will not send Dolby Digital or DTS as multi channel sound, but as Stereo PCM through these connections,

HD Audio such as TrueHD, DTS HD etc are stored in compressed form and cannot be transmitted as such. A high end DVD player will, thus, extract such sound from the disc, decode it, and mix it into muti channel PCM. This is then transmitted through HDMI 1.1 or higher connections. You have to ensure that your receiver not only has an HDMI input but should also have the ability to handle the multichannel PCM signal.

Cheers

excellent reply pal. thank u very much.

Very informative. Thanks a lot for explaining in detail.