Dish 722: Low volume on recorded programs
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Well it did load this time. Articles like this are the only reason I don't put you on the ignore list. I did a quick scan of it and I will read it all later. But it has nothing to do as to why this thread exist. It is just talking about the differences between the MPEG2 HD standard and the MPEG4. It is stating the reasons why things are shifting to MPEG4 which has better scalability and more robust hence better in situations of lossy situations.
Well it did load this time. Articles like this are the only reason I don't put you on the ignore list. I did a quick scan of it and I will read it all later. But it has nothing to do as to why this thread exist. It is just talking about the differences between the MPEG2 HD standard and the MPEG4. It is stating the reasons why things are shifting to MPEG4 which has better scalability and more robust hence better in situations of lossy situations.
Not really. Its purpose is to explain overall, or give an overview of the Scalable Video Coding extension of the H.264/AVC Standard. The title of the paper gives us the first hint of its content:
"Overview of the Scalable Video Coding Extension of the H.264/AVC Standard"
which, according to this article, not me, says:
"In January 2005, MPEG and VCEG agreed to jointly finalize the SVC project as
an Amendment of H.264/AVC within the Joint Video Team."
So it has been around since the mass roll-out of HDTV in 2006. And it says,
"The usual modes of scalability are
temporal, spatial, and quality scalability. Spatial scalability and
temporal scalability describe cases in which subsets of the bit
stream represent the source content with a reduced picture size
(spatial resolution) or frame rate (temporal resolution), respectively.
With quality scalability, the substream provides the same
spatio–temporal resolution as the complete bit stream, but with
a lower fidelity—where fidelity is often informally referred to
as signal-to-noise ratio (SNR). Quality scalability is also commonly
referred to as fidelity or SNR scalability."
While that states that Quality is directly linked to signal-to-noise ratio (which determines BER in digital systems, which determines the functioning of your system.), unfortunately, this isn't the link that has DVR/signal related information. Sorry.
Since no specifics were provided by the OP, it's difficult to describe the behavior observed. Here are a few things to help explain what MIGHT be going on.
The internal DVR records the MPEG stream without decoding so there's no way a recording can produce different video or audio than the original.
Different programs (or HD/SD versions of the same program) may be recorded at different levels, and at different average to peak ratios via audio level compression (NOT bit-rate reduction compression). Dolby Digital and DTS attempt to fix this with dialog normalization (aka dialnorm) - a parameter that identifies the apparent level of spoken word. However, dialnorm must be set properly during audio encoding and there is incentive for advertisers to set it wrong to make their content louder than the program. What I've found makes the most difference is switching between content that has a properly set dialnorm to one that has a 2-channel PCM audio that has no dialnorm and is compressed heavily to decrease the average to peak ratio to near zero. 10 dB level differences are common!
Given the same program, it's possible different outputs from the receiver (e.g. TV 1 vs TV 2) may produce different levels. Where the Dolby Digital or DTS signal is decoded may also create differences since the satellite receiver and the A/V receiver may handle the optional dynamic range parameters differently. The analog and RF outputs of the satellite receiver are obviously decoded in the satellite receiver however the HDMI and S/PDIF outputs can be set to pass the DD/DTS bitstream to the A/V receiver for decoding. RF modulation levels may also create level differences relative to the digital outputs. How an A/V receiver treats analog inputs is also a factor.
So if the "original" is viewed via HDMI and the "recorded" is viewed by the RF output there could be significant level differences.
Dolby also defines the difference between "Line" and "RF" modes. It seems reasonable the Dish receivers follow these guidelines. In Line mode, dialog is reproduced at -31 dBFS (31 dB below clipping of the digital signal). In this mode no clipping of the signal will occur. In RF mode, dialog level is reproduced at -20 dBFS which means that some program material may clip. So compression and limiting is applied to prevent clipping.
Another Dolby Digital mechanism is a dynamics range control mechanism. The "dynrng" and "compr" parameters are generated during audio encoding, and one of 5 "profiles" may be selected. dynrng is applied in the decoder when operating in "Line" mode and compr is applied in the decoder when operating in "RF" mode. The user has the ability to control how much of the dynamic range control is applied during decoding. But in the case of the Dish satellite receivers I believe these are fixed. These dynamic range reductions tend to make quieter sounds louder and loud sounds quieter (relative to the dialog reference level). So it's possible for a significant level difference to exist depending on which mode (Line or RF) and how much dynamic range control is selected in the decoder. Again, these affects will likely change from output to output.
Here is an article that explains Dolby Digital metadata:
http://www.dolby.com/uploadedFiles/...PDFs/Professional/32_JRiedmiller_NCTA2001.pdf
