On 3/6/2019 8:22 AM, Lynne wrote: > The CRC flag is only signalled once every few minutes but CRC is still > always present so the patch uses the file version instead. > CRC on 24-bit files wants non-padded samples so skip such files. > Some corrupt samples may have been output before the final check > depending on the -max_samples setting. > > > 0001-apedec-add-ability-to-check-CRC.patch > > From ad5773274448c209371dc8c70b4b21f39f968308 Mon Sep 17 00:00:00 2001 > From: Lynne <d...@lynne.ee> > Date: Wed, 6 Mar 2019 11:01:01 +0000 > Subject: [PATCH] apedec: add ability to check CRC > > The CRC flag is only signalled once every few minutes but CRC is still > always present so the patch uses the file version instead. > CRC on 24-bit files wants non-padded samples so skip such files. > Some corrupt samples may have been output before the final check > depending on the -max_samples setting. > --- > libavcodec/apedec.c | 25 ++++++++++++++++++++++++- > 1 file changed, 24 insertions(+), 1 deletion(-) > > diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c > index 15eb416ba4..3208275f6e 100644 > --- a/libavcodec/apedec.c > +++ b/libavcodec/apedec.c > @@ -24,6 +24,7 @@ > > #include "libavutil/avassert.h" > #include "libavutil/channel_layout.h" > +#include "libavutil/crc.h" > #include "libavutil/opt.h" > #include "lossless_audiodsp.h" > #include "avcodec.h" > @@ -147,7 +148,8 @@ typedef struct APEContext { > int fset; ///< which filter set to use > (calculated from compression level) > int flags; ///< global decoder flags > > - uint32_t CRC; ///< frame CRC > + uint32_t CRC; ///< signalled frame CRC > + uint32_t CRC_state; ///< accumulated CRC > int frameflags; ///< frame flags > APEPredictor predictor; ///< predictor used for final > reconstruction > > @@ -730,6 +732,7 @@ static int init_entropy_decoder(APEContext *ctx) > > /* Read the frame flags if they exist */ > ctx->frameflags = 0; > + ctx->CRC_state = ~0U;
nit: UINT32_MAX. > if ((ctx->fileversion > 3820) && (ctx->CRC & 0x80000000)) { > ctx->CRC &= ~0x80000000; > > @@ -1548,6 +1551,26 @@ static int ape_decode_frame(AVCodecContext *avctx, > void *data, > > s->samples -= blockstodecode; > > + if ((avctx->err_recognition & (AV_EF_CRCCHECK | AV_EF_COMPLIANT)) && > + (s->fileversion >= 3900) && (s->bps < 24)) { > + uint32_t crc = s->CRC_state; > + const AVCRC *crc_tab = av_crc_get_table(AV_CRC_32_IEEE_LE); > + for (i = 0; i < blockstodecode; i++) { > + for (ch = 0; ch < s->channels; ch++) { > + uint8_t *smp = frame->data[ch] + (i*(s->bps >> 3)); > + crc = av_crc(crc_tab, crc, smp, s->bps >> 3); > + } > + } > + > + if (!s->samples && ((~crc >> 1) ^ s->CRC)) { > + av_log(avctx, AV_LOG_ERROR, "CRC mismatch! Previously decoded " > + "frames may have been affected as well.\n"); > + return AVERROR_INVALIDDATA; Abort with an error only if (avctx->err_recognition & AV_EF_EXPLODE) is true. > + } > + > + s->CRC_state = crc; > + } > + > *got_frame_ptr = 1; > > return !s->samples ? avpkt->size : 0; > -- 2.21.0 > > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel