The DVD+RW Real Time Video Format

vbimport

#1

The DVD+RW Real Time Video Format

Introduction

The DVD+RW Real Time Video Format, also known as +VR or DVD+VR, is the video recording format stipulated by the DVD+RW Alliance, and supported by a great number of DVD+RW hardware and software manufacturers. This format allows adding, editing, partial deleting and partial over-writing on a DVD+RW disc, while still remaining compatible with ordinary DVD-Video players. This is different from the VR format as employed by DVD-RW recorders, which is completely different from the DVD-Video specification and hence such a disc cannot be played on a normal DVD player.

+VR also offers seamless integration of the consumer electronics and PC worlds. For example, you can record a video on a DVD+RW video recorder (and thereby using its simple operation and high quality real time video encoding), and then later on edit the video, or change the menu screens, directly on that same disc using a DVD+RW PC drive and a suitable software suite, such as neoDVD 4.0 or higher.

As the +VR format was designed to be 100% compatible with existing DVD-Video players, it does not describe the way the video and audio is supposed to be encoded. This is already covered in the DVD-Video specification. It does however describe the way the disc is supposed to behave on a DVD+RW recorder while recording, or how it should be played on a DVD-Video player.

This article will give you a closer look at some of the features of the DVD+RW Real Time Video Format, with an emphasis on the implementation of this format on a Philips DVD+RW video recorder. At the end, it also includes some information on the usage of this format on DVD+R discs.

Video modes and resolutions
The DVD+VR format supports all DVD-Video compatible recording modes and resolutions. On a DVD+RW video recorder, a user can select one of the available recording modes prior to recording. The video modes allow the user to decide whether to go for the best possible picture quality, or select a lesser degree of quality while gaining more recording time. Irrespective of the selected recording mode, all recordings are DVD-Video compatible and all can be played on a DVD-Video player.

The recording modes are:

HQ - High Quality (1 hour per side)
720 x 576 pixels - 9.72 Mbit/sec VBR

SP - Standard Play (2 hours per side)
720 x 576 pixels - 5.07 Mbit/sec VBR

SP+ - Standard Play Plus (2.5 hours per side)
720 x 576 pixels - 4.06 Mbit/sec VBR

LP - Long Play (3 hours per side)
360 x 576 pixels - 3.38 Mbit/sec VBR

EP - Extended Play (4 hours per side)
360 x 576 pixels - 2.54 Mbit/sec VBR

EP+ - Extended Play Plus (6 hours per side)
360 x 576 pixels - 1.70 Mbit/sec VBR

M8 - 8 Hour Mode (8 hours per side)
352 x 288 pixels - 1.27 Mbit/sec VBR

These values are for PAL recordings, NTSC has a vertical resolution of 480 lines instead of 576.

Not all modes are required to be available on all DVD+RW recorders. Some recorders only offer 4 or 5 recording modes. Some recorders offer additional modes (such as a 90 minutes mode, called HSP), or variable recording modes to fill the empty space of a disc with maximum quality video.

All modes can of course be played on any recorder (even the ones that don’t offer this particular recording mode) and on any DVD player.

The video modes can freely be interchanged on a single disc, i.e. one can make a recording of 1 hour in SP quality on a disc, and then add a 2 hour recording in EP format to it. At playback, the correct playback mode will be detected, even when played back on a normal DVD-Video player.

Audio will be coded using the Dolby Digital format in two-channel stereo, with a sampling rate of 48 KHz, using 16 bit per sample. Audio-quality will therefore be roughy comparable to that of a DAT-recording.

Titles and chapters
Every new recording will automatically be assigned a new chapter number, and a new entry for the recording will be added to the index picture screen (see next paragraph). All titles on a disc will be chained, that is, when playback of a title is started, all consequent titles will also be played (this way, the behaviour of a disc recorded on a DVD+RW recorder is comparable to a VCR).

Each title can be divided into chapters for easy reference. This can be done automatically by the recorder at standard intervals (about 5 minutes), or the chapter markers can be placed by the user himself. When playing back the disc on the recorder or a DVD-Video player, one can use the Next and Previous buttons on the remote control to go to the consequent chapter point. While pressing next during playback of the last chapter will advance to the beginning of the next title, since all titles are chained together.

It is also possible to divide a title into multiple titles with many recorders, an operation that usually cannot be undone afterwards. However, more recent recorders, such as the LiteOn models, allow the merging of titles on condition that the titles being merged physically follow each other (one recorded directly after the other) and that both were recorded at the same quality setting.

Please note that manual creation of chapters and titles as described above is possible with many DVD+RW recorders (such as the ones from Philips, Yamaha, Daewoo, MiCO, and others), but that some companies decided to implement this in a different way on their DVD+RW recorders (most notably Thomson/RCA and Sony).

Index Picture Screen (menus)
After the first recording is made to a blank DVD+RW disc, a menu will automatically be created that will contain an image representing the recording, along with the name of the recording, the duration of the recording, the selected recording mode and the date of recording. If the station broadcasted the program name (using for example a Teletext transmission), this name of the recording will be used, otherwise the channel name plus recording date and time will be showed. The title name can be changed into a more descriptive name by the user.

After each recording, the menu will automatically be updated and new images will be added. A menu screen of a disc recorded on a DVD+RW video recorder may contain up to 3 titles, after which an additional menu screen will be created. Again, some newer models by LiteOn enable the creation of up to six titles per menu screen. The user will be able to select one of the images on screen to select the recording that should be played, pressing down while the third image is highlighted (or the sixth if you have a LiteOn), will show the next menu screen.

The name of the individual recordings can always be changed afterwards by the user. Also the index picture, which is automatically selected upon by the recorder, can be changed by the user by selecting any of the video frames of the respective title.

If a title was erased (see “Overwriting and erasing of recordings”), it will show up as “Free space” in the title menu. Selecting such an entry for playback on the recorder or a DVD-Video player, will result in the playback of the next title. Also, if a title has been made completely “hidden” (see “Editing”), selecting this title will start the playback of the next title.

The menu will always show up on the first index screen when the disc is placed in the recorder or a DVD-Video player (see picture). Pressing Up while the first image on the first screen is highlighted will result in the showing of the Disc Menu. The Disc Menu may also contain a name (to be entered by the user), and furthermore it contains some info on the video format (PAL/NTSC) that was used on the disc, the combined recorded time, the date of the last recording and a status on whether the edits are DVD-Video compatible yet (see next paragraph).

Please note that the Index Pictures Screens as described above are used by many DVD+RW recorders (such as the ones from Philips, Yamaha, Daewoo, MiCO, and others), but that some companies decided to implement on-disc menus in a different way on their DVD+RW recorders (most notably Thomson/RCA and Sony).

Editing
Titles can be edited afterwards by dividing them into chapters and selecting which titles should be played, and which should be skipped. This way, it is for example possible to skip the commercials in a recording of a movie at playback.

When the edited title is being selected for playback on the index picture screen using the DVD+RW recorder, the edited version will always be played. The chapters that are marked “hidden” will be skipped, but chapter numbering will remain consistent with the original recording. That is, if for example chapter 2 was set hidden, the number will be skipped but the next chapter will remain to be displayed as chapter 3.

For a DVD+RW disc to play the edited titles on a DVD-Video player, the edits should first be made compatible using a menu option on the recorder. Remember that the recordings are always, immediately, DVD-Video compatible, and that only the edits need to undergo this simple operation, which will only take a few minutes. After this procedure, the titles will be played in the exact same way on a DVD-Video player as intended to by the creator. There’s one minor difference: the numbering of chapters will be continuous, hidden chapters will not be shown and are completely invisible to the viewer, hence the third chapter from the example above will be displayed as chapter 2.

Hidden chapters are not removed from the disc, they can always be “restored” at a later time, or the chapter point can be replaced to make different parts of the title invisible. The edited versions of the titles (so called “Play List Titles”) will be assigned the first title numbers on the disc. If needed, the full titles can always be played, both on the recorder and on a DVD-Video player, by manually selecting any of the title numbers after the play list titles. For example: on a disc with 5 titles, the title-numbers 1 to 5 will be assigned to the playlists (whether they are edited or not), and the title-numbers 6 trough 10 refer to the full titles. Full titles are not included in the menu, you need your player’s on-screen menus to access them.

Please note that the editing features as described above are used by many DVD+RW recorders (such as the ones from Philips, Yamaha, Daewoo, MiCO, and others), but that some companies decided to implement them in a different way on their DVD+RW recorders (most notably Thomson/RCA and Sony).

Overwriting and erasing of recordings
At any point it is possible to start recording on the disc, recording is not limited to adding new material to the end of a disc. The recording will append from the point in a title that the user has selected as the starting point of the recording. Video and audio will be added to the current title, it is not necessary to create a new title. Of course, it is always possible to divide the title into multiple separate titles later on, as mentioned before.

If a recording is being overwritten at a certain point, and the new recording does not “last” as long as the original title that is being overwritten, the last part of the original recording will still be accessible. This behaviour is identical to overwriting a recording using a standard VCR. The remaining part of the title will be assigned its own title number which will be included on the Index Picture Screen. If the new recording is longer than the original title, the following title(s), or a part of them, will be overwritten as well. If the last part of the last title that is being overwritten remains on the disc, it’s entry on the Index Picture Screen will remain. Selecting it will start playback of the part of the title that is still available on the disc.

A user may decide to erase a certain title. This operation, which cannot be undone, will free up the space taken up by the title. Free space will be shown in the Index Picture Screen as an empty image. If consequent titles will be erased, their free space will be combined into a single free space entry in the Index Picture Screen. Remember that it’s not necessary to erase a title, as they can simple be overwritten or made “hidden”. However, the option is included to erase a title from the Index Picture Screen and to prevent people from accessing it using direct title access as described under “Editing”.

Please note that direct overwriting as described above is possible many DVD+RW recorders (such as the ones from Philips, Yamaha, Daewoo, MiCO, and others), but that some companies decided to implement this in a different way on their DVD+RW recorders (most notably Thomson/RCA and Sony).

File format

A disc recorded in the DVD+VR format will be 100% compatible with the DVD-Video specification on a logical basis. That is, the locations of video and menu files will be according to this standard, and also the format and naming of the files will be exactly the same as on a pre-recorded DVD-Video disc. Recorded programs will be stored in the VIDEO_TS directory using the normal .VOB-file format. All standard DVD-Video playback software and editing or ripping utilities on a PC can be used with DVD+RW recordings.

As allowed by the DVD-Video specification, additional files will be stored on the disc containing extra information that will be used by the DVD+RW Real Time Video Format. For example, the index pictures are also stored as individual pictures so that the recorder can read them when it needs to re-create a new index picture screen (when a recording is added or changed).

PAL and NTSC recordings
Most DVD+RW recorders support for the recording in both NTSC and PAL DVD-Video format. Although the recorders have an internal tuner for a single system (i.e. PAL in Europe and NTSC in the US), they will accept the other video format from an external source (such as a camcorder or VCR) and record this video as such. For playback, the DVD-Video player or the connected TV set must support this foreign format.

Since it is not possible to combine PAL and NTSC on a single disc according to the DVD-Video specification, the first recording will determine the “format” of the disc. This format will also be shown on the Disc Menu that can be accessed by pressing “Up” on the first menu page, on both the recorder and a DVD-Video player. Of course, when the disc will be completely erased, the other format can be used for recording on this disc.

Region coding
Recordings made on a DVD+RW video recorder have the region coding flag set to “off”, hence the discs are not region protected in any way. A recording made on a European DVD+RW video recorder can for example be played on any DVD-Video player, even a US model.

Keep in mind however that most US DVD-Video players do not play PAL DVD-discs, so that a PAL recording can not be played. Most European DVD-Video players accept discs in both PAL and NTSC format, but depending on their output format, they also need a multi-standard TV set for playback.

Subpicture
Every recording made on a DVD+RW video recorder will contain a subpicture stream along with the recording. Subpictures are used by DVD-Video discs to show subtitles among others.

Every DVD+VR recording contains at least one subpicture stream with each recording. This can be empty, however some DVD+RW video recorders use it to store additional information when a recording is made from the DV or i.Link input. In this case, the original time and date are stored, which can be recalled on any DVD-Video player by pressing the subtitle button.

Aspect ratio
Usually, all recordings made with a DVD+RW video recorder have a screen aspect ratio of 4:3. When you record video from an anamorphic widescreen source (such as a DV camcorder recording made in “16:9 Wide” mode, or a 16:9 enhanced DVD), it will be recorded as such in anamorphic format on the disc. The recorder will include an extra flag in the video stream that will allow the recorder to signal the TV to switch to “widescreen” mode when playing back the disc.

Keep in mind however that this is a DVD+RW “special feature”, that is not defined by the DVD-Video specification. Hence, a DVD-Video player will not signal the TV to switch to widescreen mode, you have to do this manually. The video will also not be scaled to letterbox format when being played on a DVD player that is set to 4:3 Letterbox mode. This is all due to the fact that the DVD-Video specification does not allow for the changing of “normal” and “widescreen” mode within a single title. Since it cannot be guaranteed that a title recorded in widescreen will not contain 4:3 video at a later time, the official “anamorphic” flag will not be included, otherwise the possible 4:3 video in that same title will be showed “stretched”. Of course during playback on a DVD+RW video recorder, there can be a mixture of signals to indicate widescreen and 4:3 video.

When recording a widescreen TV-program, such as a PALplus transmission (that is, a letterboxed 16:9 TV-broadcast common in Europe that signals a 16:9 “zoom” command to widescreen TVs), the video will be recorded in full screen 4:3 mode, including the black bars, so that it will play correctly on any TV set. Also in this case, the “zoom”-command will be stored as a DVD+RW exclusive extra, so that playing back such a recording using a DVD+RW recorder will trigger the TV to zoom in on the actual picture.

+VR format on DVD+R discs

Although the DVD+VR format was specifically designed to support all of the unique features of DVD+RW, it is also employed on DVD+R discs that are recorded in a DVD+RW video recorder. A DVD+R disc recorded on such a recorder is 100% compatible with the DVD+VR format, and hence with the DVD-Video specification.

However, due to the nature of a “write-once” disc, some features are not available, or are implemented differently. You can of course not overwrite parts of a recording. Any new recording is always added to the end of the disc. Furthermore, it’s impossible to divide a title into multiple titles, since this requires an update in the video stream. Likewise, you cannot add chapter stops in a recording, as this also requires a change in the video stream. However, if the recorders offers this functionality, you can add chapters in a DVD+R recording afterwards, but these can not be made DVD-Video compatible. You can only access them when the disc is played on the recorder, and hence they should be considered as a convenience feature.

You can change the picture that is used on the Index Picture Screen, as well as the program name, in a similar fashion as on a DVD+RW disc.

In order to play a DVD+R disc that was recorded on a DVD+RW video recorder on a normal DVD-Video player, it needs to be finalised. This procedure, that is not necessary with DVD+RW discs, makes the disc compatible, and prevents you from making further changes to it. Once the disc is finalized, it will start playback immediately upon loading it in the recorder (contrary to DVD+RW discs, which show the Index Picture Screen by default).

It is good to know that it’s perfectly well possible to make a duplicate of a DVD+R disc on a DVD+RW disc using a DVD+RW PC drive and some copy tool. Since the original DVD+R disc was also made according to the +VR format, you can now perform all of the special features on the DVD+RW duplicate, such as making the chapter stops compatible, or partially overwrite recordings.

This article is an edited version of that which previously appeared on the DVDplusRW forum, and unless I hear different, should be largely credited to Jorg Kennis :cool: . There is a previous declaration that it is also partly based on information from the user manual for the DVD+RW Real Time Video Format Test Disc, which was available from the Philips Intellectual Property & Standards website.

Thanks also to Seán for help with editing… :slight_smile:


DVD+VR format