Setting the record HD resolution?

[zeil999]

Is there a setting in the TiVoHD where you can specify what resolution you want HD shows to be recorded in? For example: Some shows come in at 1080i and they record in that resolution. But I want the TiVo to record the shows in 720p instead. Is this possible? I was wanting to try to keep the files sizes down as much as possible but keep it in HD. After transferring the shows to Toast, it seems that 720p shows after cutting out commercials will fit on one DVD no problem.

[bkdtv]

All digital channels are recorded, bit-for-bit identical to the original broadcast. The TiVo has no way to modify the digital signal. The output format is a separate setting under Settings -> Video -> Output Format.

If you want to reduce the size of the recordings, you'll need to convert them with your computer, preferably using a more efficient codec like VC-1 or MPEG-4 AVC. That assumes you want to keep them in high-definition for a Blu-ray disk. DVD players do not support high-definition playback.

[bkdtv]

To add to the above, I would note that re-encoding is a very computational process, as you will see when re-encoding with a computer.

To do what you want, the TiVo would have to re-encode HD in real-time, and there's no way the typical 300MHz DVR CPU could do that. Real-time re-encoding that can maintain good quality would would require a dedicated, high-performance MP@HL encoder and that is not the sort of technology you are going to find in a $300 device like the TiVo.

[ThAbtO]

Only recordings set from SD analog channels will be able to set the video quality.

[sinanju]

Only recordings set from SD analog channels will be able to set the video quality.

Actually, one can only set the quality on analog channels. Digital, both SD and HD are recorded as-is.

[ciper]

The Tivo HD is basically an upgraded version of the old satellite Tivos, except they understand QAM and have an encoder for analog video. The Video encoder in the Tivo HD is not capable of 720p encoding.

[sinanju]

The Tivo HD is basically an upgraded version of the old satellite Tivos, except they understand QAM and have an encoder for analog video.


The physical architecture of the TiVo HD is not similar to that of the old satellite TiVos.


The Video encoder in the Tivo HD is not capable of 720p encoding.

!?

The TiVo HD is capable of recording 720p. It isn't capable of transcoding from some resolution to 720p. But, neither is it capable of transcoding from 720p to any other resolution.

There is nothing special about 720p.

[ciper]

The physical architecture of the TiVo HD is not similar to that of the old satellite TiVos.
I didn't use the term physical but lets go with it. The satellite Tivo's were special at the time because they didn't have a video encoder at all. The data stream was directly dumped to disk. This is exactly what the S3 Tivos do with digital streams.


The TiVo HD is capable of recording 720p. It isn't capable of transcoding from some resolution to 720p. But, neither is it capable of transcoding from 720p to any other resolution.
Did you even read the sentence that you quoted?!
The Video encoder in the Tivo HD is not capable of 720p encoding.
Transcoding and Encoding are interchangeable in this scenario.

[zeil999]

If I'm not mistaken, but most HD TVs have the ability to choose what resolution to output on the screen as the signal is coming through, am I correct? Like a signal that's normally 1080i can be put on the screen at 720p by the TV. That's why I thought it would be a simple setting of only accepting a particular resolution coming into the TiVo and recording it as it's coming in at that particular resolution. Know what I mean?

[wmcbrine]

Sorry, but you are mistaken. :) The TV doesn't work that way. If we're talking about a modern plasma or LCD panel, for example, it has one, fixed resolution, to which it converts all inputs. It can accept 720p, 1080i, or 480i/p, but it doesn't convert between them; it converts them all to its native resolution.

What you're probably thinking of is the output from a device like TiVo, which can convert between 1080i and 720p, and do it in real time. But that's the easy part. The video is sent to the TV uncompressed (or in analog, even, if you're using component). The hard part is the MPEG encoding stage, which takes that enormous, uncompressed digital video and squeezes it down to something that will fit on a hard drive. The TiVo can do that in real time, too; but only for 480i.

There's no theoretical reason why a TiVo couldn't be built with the ability to encode to 720p or 1080i (using current components -- it was probably impractical when the S3 and HD were designed), but so far, they haven't been. And, the case for transcoding between 1080i and 720p is not compelling -- you'd lose quality, and you wouldn't gain that much space.