scheda video per h.264

[lorenzo82]

Il mio HTPC è attualmente così composto:
processore amd athlon 64 bit 3,2GHz
scheda video nvidia 6600gt agp 128MB
ram 1GB
scheda audio X-Mystique

Ho da poco scaricato un filmato codificato in h.264 ma non sono riuscito a vederlo perchè scattava in maniera paurosa.
Ho utilizzato theatertek 2.4 con driver nvidia 91.31 e ffdshow come decoder...
Mi chiedevo se cambiando scheda video e utilizzando coreavc o un altro decoder che abiliti la dxva per gli h264 si possa riuscire a vedere questi filmati senza scatti...
Che scheda mi consigliate, rimanendo su nvidia con connessione agp, che abbia la dxva per gli h264 e sia in grado di riprodurre in modo fluido materiale in alta definizione fino a risoluzione 1080p, senza cambiare processore, e che abbia anche l'uscita component?
Lorenzo.

[PynkyZ]

Ora come ora credo nessuna. A parte le affermazioni di facciata, nessuna scheda video può da sola garantirti un'accelerazione HW tale da vedere filmati H.264 ad altissima qualità, ci vuole cmq una CPU molto potente. Un domani, con driver più maturi allora forse le cose cambieranno...

[jok]

Il mio HTPC è attualmente così composto:
processore amd athlon 64 bit 3,2GHz
scheda video nvidia 6600gt agp 128MB
ram 1GB
scheda audio X-Mystique

Ho da poco scaricato un filmato codificato in h.264 ma non sono riuscito a vederlo perchè scattava in maniera paurosa.
Ho utilizzato theatertek 2.4 con driver nvidia 91.31 e ffdshow come decoder...

A quanto pare non sei ancora riucisto ad ottenere l'accelerazione hardware con la tua 6600... ti consiglio prima di cercare di ottenerla (con la tua CPU e scheda video è possibile), e poi eventualmente cercare un'altra CPU piuttosto che un'altra scheda video.

Ciao,
Jok

[lorenzo82]

Se devo cambiare processore è per passare a un dual core e ciò comporterebbe anche il cambio di scheda madre cosa che, per ora, vorrei evitare mentre un cambio di scheda video sarebbe completamente indolore in quanto a smanettamenti hardware e software...
Quindi dite che la scheda video, da sola, non ce la fa a sopportare la decodifica hardware di materiale h.264? Possibile che, ad esempio, una 7900, con accoppiato un 3,2GHz non ce la fa a farmi vedere fluido un filmato 1080p in h.264?
Lorenzo.

[lorenzo82]

Ho dato un'occhiata in giro e ho trovato una proposta interessante: la 7600gt agp, sembra avere caratteristiche eccellenti per uso htpc, anche superiori alla 7800gs agp...
Lorenzo.

[PynkyZ]

Dipende dal filmato: non è che un filmato 1080p sia uguale a un altro....H.264 offre 3 diversi profili di codifica (che in verità poi sono ben 7) più tante altre variabili. Con la combinazione più intensiva possibile, probabilmente no, non ce la farebbe neanche con quella scheda video, no.
"H.264/AVC/MPEG-4 Part 10 contains a number of new features that allow it to compress video much more effectively than older standards and to provide more flexibility for application to a wide variety of network environments. In particular, some such key features include:
Multi-picture motion compensation using previously-encoded pictures as references in a much more flexible way than in past standards, thus allowing up to 32 reference pictures to be used in some cases (unlike in prior standards, where the limit was typically one or, in the case of conventional "B pictures", two). This particular feature usually allows modest improvements in bit rate and quality in most scenes. But in certain types of scenes, for example scenes with rapid repetitive flashing or back-and-forth scene cuts or uncovered background areas, it allows a very significant reduction in bit rate.
Variable block-size motion compensation (VBSMC) with block sizes as large as 16×16 and as small as 4×4, enabling very precise segmentation of moving regions.
Six-tap filtering for derivation of half-pel luma sample predictions, in order to lessen the aliasing and eventually provide sharper images.
Macroblock pair structure (not supported in all profiles), allowing 16x16 macroblocks in field mode (vs. 16x8 half-macroblocks in MPEG-2).
Quarter-pixel precision for motion compensation, enabling very precise description of the displacements of moving areas. For chroma the resolution is typically halved both vertically and horizontally (see 4:2:0) therefore the motion compensation precision is down to one-eighth pixel.
Weighted prediction, allowing an encoder to specify the use of a scaling and offset when performing motion compensation, and providing a significant benefit in performance in special cases—such as fade-to-black, fade-in, and cross-fade transitions.
Spatial prediction from the edges of neighboring blocks for "intra" coding (rather than the "DC"-only prediction found in MPEG-2 Part 2 and the transform coefficient prediction found in H.263+ and MPEG-4 Part 2).
An in-loop deblocking filter which helps prevent the blocking artifacts common to other DCT-based image compression techniques.
An exact-match integer 4×4 spatial block transform (similar to the well-known DCT design), allowing precise placement of residual signals with little of the "ringing" often found with prior codec designs.
An exact-match integer 8×8 spatial block transform (similar to the well-known DCT design, not supported in all profiles), allowing correlated regions to be compressed more efficiently than with the 4×4 transform.
Adaptive encoder selection between the 4×4 and 8×8 transform block sizes for the integer transform operation (not supported in all profiles).
A secondary Hadamard transform performed on "DC" coefficients of the primary spatial transform (for chroma DC coefficients and also luma in one special case) to obtain even more compression in smooth regions.
Logarithmic step size control for easier bit rate management by encoders and simplified inverse-quantization scaling.
Frequency-customized quantization scaling matrices selected by the encoder for perceptual-based quantization optimization (not supported in all profiles).
A lossless PCM macroblock representation mode in which video data samples are represented directly, allowing perfect representation of specific regions and allowing a strict limit to be placed on the quantity of coded data for each macroblock.
An enhanced lossless macroblock representation mode allowing perfect representation of specific regions while ordinarily using substantially fewer bits than the PCM mode (not supported in all profiles).
Context-adaptive binary arithmetic coding (CABAC), which is a clever technique to losslessly compress syntax elements in the video stream knowing the probabilities of syntax elements in a given context (not supported in all profiles).
Context-adaptive variable-length coding (CAVLC), which is a lower-complexity alternative to CABAC for the coding of quantized transform coefficient values. Although lower complexity than CABAC, CAVLC is more elaborate and more efficient than the methods typically used to code coefficients in other prior designs.
A common simple and highly-structured variable length coding (VLC) technique for many of the syntax elements not coded by CABAC or CAVLC, referred to as Exponential-Golomb (Exp-Golomb) coding.
A network abstraction layer (NAL) definition allowing the same video syntax to be used in many network environments, including features such as sequence parameter sets (SPSs) and picture parameter sets (PPSs) that provide more robustness and flexibility than provided in prior designs.
Switching slices (called SP and SI slices and not supported in all profiles), features that allow an encoder to direct a decoder to jump into an ongoing video stream for such purposes as video streaming bit rate switching and "trick mode" operation. When a decoder jumps into the middle of a video stream using the SP/SI feature, it can get an exact match to the decoded pictures at that location in the video stream despite using different pictures (or no pictures at all) as references prior to the switch.
Flexible macroblock ordering (FMO, also known as slice groups and not supported in all profiles) and arbitrary slice ordering (ASO), which are techniques for restructuring the ordering of the representation of the fundamental regions (called macroblocks) in pictures. Typically considered an error/loss robustness feature, FMO and ASO can also be used for other purposes.
Data partitioning (DP), a feature providing the ability to separate more important and less important syntax elements into different packets of data, enabling the application of unequal error protection (UEP) and other types of improvement of error/loss robustness (not supported in all profiles).
Redundant slices (RS), an error/loss robustness feature allowing an encoder to send an extra representation of a picture region (typically at lower fidelity) that can be used if the primary representation is corrupted or lost (not supported in all profiles).
A simple automatic process for preventing the accidental emulation of start codes, which are special sequences of bits in the coded data that allow random access into the bitstream and recovery of byte alignment in systems that can lose byte synchronization.
Supplemental enhancement information (SEI) and video usability information (VUI), which are extra information that can be inserted into the bitstream to enhance the use of the video for a wide variety of purposes.
Auxiliary pictures, which can be used for such purposes as alpha compositing.
Frame numbering, a feature that allows the creation of "sub-sequences" (enabling temporal scalability by optional inclusion of extra pictures between other pictures), and the detection and concealment of losses of entire pictures (which can occur due to network packet losses or channel errors).
Picture order count, a feature that serves to keep the ordering of the pictures and the values of samples in the decoded pictures isolated from timing information (allowing timing information to be carried and controlled/changed separately by a system without affecting decoded picture content).
These techniques, along with several others, help H.264 to perform significantly better than any prior standard can, under a wide variety of circumstances in a wide variety of application environments. H.264 can often perform radically better than MPEG-2 video—typically obtaining the same quality at half of the bit rate or less.

Like other ISO/IEC MPEG video standards, H.264/AVC has a reference software implementation that can be freely downloaded. Its main purpose is to give examples of H.264/AVC features, rather than being a useful application per se. (See the links section for a pointer to that software.) Some reference hardware design work is also under way in MPEG.

Profiles
The standard includes the following seven sets of capabilities, which are referred to as profiles, targeting specific classes of applications:

Baseline Profile (BP): Primarily for lower-cost applications demanding less computing resources, this profile is used widely in videoconferencing and mobile applications.
Main Profile (MP): Originally intended as the mainstream consumer profile for broadcast and storage applications, the importance of this profile faded when the High profile was developed for those applications.
Extended Profile (XP): Intended as the streaming video profile, this profile has relatively high compression capability and some extra tricks for robustness to data losses and server stream switching.
High Profile (HiP): The primary profile for broadcast and disc storage applications, particularly for high-definition television applications (this is the profile adopted into HD DVD and Blu-ray Disc, for example).
High 10 Profile (Hi10P): Going beyond today's mainstream consumer product capabilities, this profile builds on top of the High Profile — adding support for up to 10 bits per sample of decoded picture precision.
High 4:2:2 Profile (Hi422P): Primarily targeting professional applications that use interlaced video, this profile builds on top of the High 10 Profile — adding support for the 4:2:2 chroma sampling format while using up to 10 bits per sample of decoded picture precision.
High 4:4:4 Profile (Hi444P) [deprecated]: This profile builds on top of the High 4:2:2 Profile — supporting up to 4:4:4 chroma sampling, up to 12 bits per sample, and additionally supporting efficient lossless region coding and an integer residual color transform for coding RGB video while avoiding color-space transformation error. Note: The High 4:4:4 Profile is being removed from the standard in favor of developing a new improved 4:4:4 profile."

[lorenzo82]

Lorenzo.

[lorenzo82]

Piccolo ot:
Se cambio processore e/o scheda madre dovrei reinstallare il S.O. e rifare l'immagine con ghost o funzionerebbe anche la vecchia immagine?
Fine ot.
Lorenzo.

[PynkyZ]

Teoricamente sarebbe possibile senza dover reinstallare, in pratica è un rebus: può andar bene come no.

[Giakko]

Lorenzo, ti consiglio di provare VLC Video lan player.

E' gratuito ed ha un codec h264 open source che funziona benissimo.

Sul mio athlonXP2400+ riesco a vedere i filmati h264 di trailer quicktime perfettamente a 720p.

Non ho provato i 1080p, ma con la tua cpu non ci dovrebbero essere problemi.

Ovviamente con il quicktime i filmati 720p suddetti sono inguardabili.

Prova e facci sapere!

http://www.videolan.org/

[PynkyZ]

Faccio notare che i trailer in H.264 di solito sono codificati con il profilo ed con le opzioni meno complessi proprio per essere i più "leggeri" possibili per le risorse di un computer.

[Giakko]

Lorenzo, hai provato il "Vlc"?

Ricordo che fa una accellerazione software e non serve impostare niente....basta installarlo e provarlo.

Credo che sia la soluzione migliore per provare i file h264 con pc poco prestanti.

Ciao!

[PynkyZ]

Una domanda relativa: qualcuno può scrivere quali versioni dei Catalyst hanno supporto per H.264 Hw e quali no (fra le ultime release intendo) per favore.