On Sun, Jan 08, 2017 at 12:07:09PM +0100, Steinar H. Gunderson wrote: > This decoder can decode all existing SpeedHQ formats (SHQ0–5, 7, and 9), > including correct decoding of the alpha channel. > > 1080p is decoded in 142 fps on one core of my i7-4600U (2.1 GHz Haswell), > about evenly split between bitstream reader and IDCT. There is currently > no attempt at slice or frame threading, even though the format trivially > supports both. > > NewTek very helpfully provided a full set of SHQ samples, as well as > source code for an SHQ2 encoder (not included) and assistance with > understanding some details of the format. > --- [...]
> +static av_cold int speedhq_decode_init(AVCodecContext *avctx)
> +{
> + static int done = 0;
> + uint16_t ff_mpeg12_vlc_dc_lum_code_reversed[12];
> + uint16_t ff_mpeg12_vlc_dc_chroma_code_reversed[12];
> + SHQContext * const s = avctx->priv_data;
> +
> + s->avctx = avctx;
> +
> + if (!done) {
> + int i;
> +
> + /* Exactly the same as MPEG-2, except little-endian. */
> + reverse_code(ff_mpeg12_vlc_dc_lum_code,
> + ff_mpeg12_vlc_dc_lum_bits,
> + ff_mpeg12_vlc_dc_lum_code_reversed,
> + 12);
> + INIT_LE_VLC_STATIC(&ff_dc_lum_vlc_le, DC_VLC_BITS, 12,
> + ff_mpeg12_vlc_dc_lum_bits, 1, 1,
> + ff_mpeg12_vlc_dc_lum_code_reversed, 2, 2, 512);
> + reverse_code(ff_mpeg12_vlc_dc_chroma_code,
> + ff_mpeg12_vlc_dc_chroma_bits,
> + ff_mpeg12_vlc_dc_chroma_code_reversed,
> + 12);
> + INIT_LE_VLC_STATIC(&ff_dc_chroma_vlc_le, DC_VLC_BITS, 12,
> + ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
> + ff_mpeg12_vlc_dc_chroma_code_reversed, 2, 2, 514);
> +
> + /* Reverse the AC VLC, because INIT_VLC_LE wants it in that order. */
> + for (i = 0; i < FF_ARRAY_ELEMS(speedhq_vlc); ++i) {
> + speedhq_vlc[i][0] = reverse(speedhq_vlc[i][0],
> speedhq_vlc[i][1]);
> + }
This makes the init thread unsafe
it would be better if the table was const and this wasnt done at
runtime
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
The worst form of inequality is to try to make unequal things equal.
-- Aristotle
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