On 2/17/2024 11:44 PM, Andreas Rheinhardt wrote:
AVCodecParameters.extradata is supposed to be allocated with
av_malloc(); av_realloc() and its wrappers do not guarantee
the proper alignment. Therefore parse the extradata twice:
Once to check its validity and to determine the eventual size
and a second time to actually write the new extradata.
Why would av_malloc alignment be needed for extradata?
I see the doxy says "Must be allocated with av_malloc()" but I'm fairly
sure that was meant to be "Must be allocated with av_malloc() family of
functions", like its AVCodecContext counterpart. The idea is that
library users don't use normal malloc as extradata will be freed with
av_free(), and not because it will be accessed by SIMD code.
(Of course, not reallocating the buffer is beneficial in itself.)
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
---
libavcodec/bsf/hevc_mp4toannexb.c | 44 +++++++++++++++----------------
1 file changed, 22 insertions(+), 22 deletions(-)
diff --git a/libavcodec/bsf/hevc_mp4toannexb.c
b/libavcodec/bsf/hevc_mp4toannexb.c
index a695cba370..f5424e95b8 100644
--- a/libavcodec/bsf/hevc_mp4toannexb.c
+++ b/libavcodec/bsf/hevc_mp4toannexb.c
@@ -38,13 +38,11 @@ typedef struct HEVCBSFContext {
} HEVCBSFContext;
static int hevc_extradata_to_annexb_internal(void *logctx, GetByteContext *gb,
- uint8_t **new_extradatap,
+ uint8_t *new_extradata,
size_t *new_extradata_sizep)
{
int num_arrays = bytestream2_get_byte(gb);
- uint8_t *new_extradata = NULL;
size_t new_extradata_size = 0;
- int ret;
for (int i = 0; i < num_arrays; i++) {
int type = bytestream2_get_byte(gb) & 0x3f;
@@ -54,8 +52,7 @@ static int hevc_extradata_to_annexb_internal(void *logctx,
GetByteContext *gb,
type == HEVC_NAL_SEI_PREFIX || type == HEVC_NAL_SEI_SUFFIX)) {
av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit type in extradata:
%d\n",
type);
- ret = AVERROR_INVALIDDATA;
- goto fail;
+ return AVERROR_INVALIDDATA;
}
for (int j = 0; j < cnt; j++) {
@@ -64,26 +61,19 @@ static int hevc_extradata_to_annexb_internal(void *logctx,
GetByteContext *gb,
if (!nalu_len ||
nalu_len > bytestream2_get_bytes_left(gb) ||
4 + nalu_len > FFMIN(INT_MAX, SIZE_MAX) -
AV_INPUT_BUFFER_PADDING_SIZE - new_extradata_size) {
- ret = AVERROR_INVALIDDATA;
- goto fail;
+ return AVERROR_INVALIDDATA;
}
- ret = av_reallocp(&new_extradata, new_extradata_size + nalu_len +
4 + AV_INPUT_BUFFER_PADDING_SIZE);
- if (ret < 0)
- goto fail;
-
- AV_WB32(new_extradata + new_extradata_size, 1); // add the
startcode
- bytestream2_get_buffer(gb, new_extradata + new_extradata_size + 4,
nalu_len);
+ if (new_extradata) {
+ AV_WB32(new_extradata + new_extradata_size, 1); // add the
startcode
+ bytestream2_get_bufferu(gb, new_extradata + new_extradata_size
+ 4, nalu_len);
+ } else
+ bytestream2_skipu(gb, nalu_len);
new_extradata_size += 4 + nalu_len;
- memset(new_extradata + new_extradata_size, 0,
AV_INPUT_BUFFER_PADDING_SIZE);
}
}
- *new_extradatap = new_extradata;
*new_extradata_sizep = new_extradata_size;
return 0;
-fail:
- av_freep(&new_extradata);
- return ret;
}
static int hevc_extradata_to_annexb(AVBSFContext *ctx)
@@ -100,10 +90,20 @@ static int hevc_extradata_to_annexb(AVBSFContext *ctx)
bytestream2_skip(&gb, 21);
length_size = (bytestream2_get_byte(&gb) & 3) + 1;
- ret = hevc_extradata_to_annexb_internal(ctx, &gb, &new_extradata,
- &new_extradata_size);
- if (ret < 0)
- return ret;
+ while (1) {
+ GetByteContext gb_bak = gb;
+ ret = hevc_extradata_to_annexb_internal(ctx, &gb, new_extradata,
+ &new_extradata_size);
+ if (ret < 0)
+ return ret;
+ if (new_extradata || !new_extradata_size)
+ break;
+ new_extradata = av_malloc(new_extradata_size +
AV_INPUT_BUFFER_PADDING_SIZE);
+ if (!new_extradata)
+ return AVERROR(ENOMEM);
+ memset(new_extradata + new_extradata_size, 0,
AV_INPUT_BUFFER_PADDING_SIZE);
+ gb = gb_bak;
+ }
av_freep(&ctx->par_out->extradata);
ctx->par_out->extradata = new_extradata;
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