[Mp4-tech] "blocky" shown while playing .mp4 file

[Parag Chaurasia]

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  Hi John,
    There could be a variety of reasons for this:
(1)  In MPEG-4 Simple Profile, the max bit rate that a decoder is required to support is 384 kbps. 950 kbps is too high a value, and it's diffucult to say how the MPEG-4 decoder used in QuickTime 6.3 Player or RealOne Player will react.
(2)  Blockiness may also result if the Rate Control Algorithm used in that MPEG-4 Encoder is not up to the mark for some particular cases, like in this instance, 950 kbps and QVGA encoding.
(3)  Your PC Specifications, as far as Processor Speed is concerned, are at a lower end. What is the frame rate of the MPEG-4 video stream? If fps is large and given the fact that bit rate is also high and VOL width/height is 320 x 240, then playback may not be as desired....
  I suggest that you decode the MPEG-4 Simple Profile bitstream using an MPEG-4 reference video decoder and play the decoded sequence in some YUV 4:2:0 player....
  Regards,
  Parag.
On Mon, 12 Jan 2024 John Lam wrote :
>Hi all,
>
>I've mpeg4 visual stream conformed to ISO/IEC 14496-2 simple profile,
>its resolution is QVGA and bit rate is about 950kbps. I constructed .mp4
>file header for this visual stream, then I can play it using QuickTime
>6.3 and RealOne player. However, I find that there is "blocky" effect
>for some instances while playing it in both QuickTime and RealOne
>player. I wonder if it is caused by my out-dated computer configuration
>or something else. Does anyone has clue on it? I can send the file to
>you to view the actual "blocky" effect. Does anyone know what is the
>computer configuration requirement for playing such visual stream by
>QuickTime or RealOne player? Thank you!
>
>My computer config:
>1. Pentium III 500MHz
>2. 128MB SDRAM
>3. SCSI hard disk with 150MB free space.
>
>--
>Best Regards,
>John Lam
>
>
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