Carl Eugen Hoyos (12020-04-25): > Hi! > > Attached patch allows reading the pgm file that jasper creates > using the jpeg 2000 reference file p0_03.j2k as input. > > Please comment, Carl Eugen
> From 5da97c417d66b1e840b1feae31f0852cf3755c39 Mon Sep 17 00:00:00 2001 > From: Carl Eugen Hoyos <[email protected]> > Date: Sat, 25 Apr 2020 17:05:40 +0200 > Subject: [PATCH] lavc/pnm: Allow reading signed pgm values as written by > jasper. > > --- > libavcodec/pnm.c | 4 ++++ > libavcodec/pnm.h | 1 + > libavcodec/pnmdec.c | 2 +- > 3 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/libavcodec/pnm.c b/libavcodec/pnm.c > index b5c2881948..c9b9eb9ccd 100644 > --- a/libavcodec/pnm.c > +++ b/libavcodec/pnm.c > @@ -176,6 +176,10 @@ int ff_pnm_decode_header(AVCodecContext *avctx, > PNMContext * const s) > if (avctx->pix_fmt != AV_PIX_FMT_MONOWHITE && avctx->pix_fmt != > AV_PIX_FMT_MONOBLACK) { > pnm_get(s, buf1, sizeof(buf1)); > s->maxval = atoi(buf1); > + if (s->maxval < 0) { > + s->maxval *= -1; > + s->jasper_signed = 1; > + } > if (s->maxval <= 0 || s->maxval > UINT16_MAX) { The s->maxval <= 0 test here has become redundant. I do not know if the patch itself is correct and wanted. > av_log(avctx, AV_LOG_ERROR, "Invalid maxval: %d\n", s->maxval); > s->maxval = 255; > diff --git a/libavcodec/pnm.h b/libavcodec/pnm.h > index 5bc0aad29f..2550cef92b 100644 > --- a/libavcodec/pnm.h > +++ b/libavcodec/pnm.h > @@ -30,6 +30,7 @@ typedef struct PNMContext { > uint8_t *bytestream_end; > int maxval; ///< maximum value of a pixel > int type; > + int jasper_signed; > } PNMContext; > > int ff_pnm_decode_header(AVCodecContext *avctx, PNMContext * const s); > diff --git a/libavcodec/pnmdec.c b/libavcodec/pnmdec.c > index dbcaef3884..6e5f5b6c3b 100644 > --- a/libavcodec/pnmdec.c > +++ b/libavcodec/pnmdec.c > @@ -168,7 +168,7 @@ static int pnm_decode_frame(AVCodecContext *avctx, void > *data, > else if (upgrade == 1) { > unsigned int j, f = (255 * 128 + s->maxval / 2) / s->maxval; > for (j = 0; j < n; j++) > - ptr[j] = (s->bytestream[j] * f + 64) >> 7; > + ptr[j] = ((s->bytestream[j] - (s->maxval / 2 - 1) * > s->jasper_signed) * f + 64) >> 7; > } else if (upgrade == 2) { > unsigned int j, v, f = (65535 * 32768 + s->maxval / 2) / > s->maxval; > for (j = 0; j < n / 2; j++) { Regards, -- Nicolas George
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