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apedec: add ability to check CRC

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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.
This commit is contained in:
Lynne 2019-03-06 11:01:01 +00:00
parent 731c775898
commit 1cc8eecd38
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GPG Key ID: A2FEA5F03F034464
1 changed files with 25 additions and 1 deletions
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26
libavcodec/apedec.c
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@ -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
@ -750,6 +752,7 @@ static int init_entropy_decoder(APEContext *ctx)
/* Read the frame flags if they exist */
ctx->frameflags = 0;
ctx->CRC_state = UINT32_MAX;
if ((ctx->fileversion > 3820) && (ctx->CRC & 0x80000000)) {
ctx->CRC &= ~0x80000000;
@ -1577,6 +1580,27 @@ static int ape_decode_frame(AVCodecContext *avctx, void *data,
s->samples -= blockstodecode;
if (avctx->err_recognition & AV_EF_CRCCHECK &&
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");
if (avctx->err_recognition & AV_EF_EXPLODE)
return AVERROR_INVALIDDATA;
}
s->CRC_state = crc;
}
*got_frame_ptr = 1;
return !s->samples ? avpkt->size : 0;