[FFmpeg-devel] 回复: [PATCH v1 09/19] avcodec/h274: add ff_h274_hash functions

[Wu Jianhua]

Andreas Rheinhardt:
> toqsxw at gmail.com:
>> From: Wu Jianhua <toqsxw at outlook.com>
>>
>> Signed-off-by: Wu Jianhua <toqsxw at outlook.com>
>> ---
>>  libavcodec/h274.c | 163 ++++++++++++++++++++++++++++++++++++++++++++++
>>  libavcodec/h274.h |   7 ++
>>  2 files changed, 170 insertions(+)
>>
>> diff --git a/libavcodec/h274.c b/libavcodec/h274.c
>> index 5709200322..9edc705042 100644
>> --- a/libavcodec/h274.c
>> +++ b/libavcodec/h274.c
>> @@ -26,7 +26,11 @@
>>   */
>>
>>  #include "libavutil/avassert.h"
>> +#include "libavutil/bswap.h"
>> +#include "libavutil/crc.h"
>>  #include "libavutil/imgutils.h"
>> +#include "libavutil/md5.h"
>> +#include "libavutil/mem.h"
>>
>>  #include "h274.h"
>>
>> @@ -790,3 +794,162 @@ static const int8_t R64T[64][64] = {
>>           17, -16,  15, -14,  13, -12,  11, -10,   9,  -8,   7,  -6,   4,  -3,   2,  -1,
>>      }
>>  };
>> +
>> +static int verify_plane_md5(struct AVMD5 *ctx,
>> +    const uint8_t *src, const int w, const int h, const int stride,
>> +    const uint8_t *expected)
>> +{
>> +#define MD5_SIZE 16
>> +    uint8_t md5[MD5_SIZE];
>> +    av_md5_init(ctx);
>> +    for (int j = 0; j < h; j++) {
>> +        av_md5_update(ctx, src, w);
>> +        src += stride;
>> +    }
>> +    av_md5_final(ctx, md5);
>> +
>> +    if (memcmp(md5, expected, MD5_SIZE))
>> +        return AVERROR_INVALIDDATA;
>> +
>> +    return 0;
>> +}
>> +
>> +static int verify_plane_crc(const uint8_t *src, const int w, const int h, const int stride,
>> +    const uint8_t *expected)
>> +{
>> +    uint32_t crc = 0x0F1D;     // CRC-16-CCITT-AUG
>> +    const AVCRC *ctx = av_crc_get_table(AV_CRC_16_CCITT);
>> +
>> +    for (int j = 0; j < h; j++) {
>> +        crc = av_crc(ctx, crc, src, w);
>> +        src += stride;
>> +    }
>> +    crc = av_bswap16(crc);
>> +
>> +    if (memcmp(&crc, expected, sizeof(uint16_t)))
>
> This seems endian-dependent (as are the other checks). Why don't you
> simply pass the proper CRC as uint16_t/uint32_t parameter?
>
>> +        return AVERROR_INVALIDDATA;
>> +
>> +    return 0;
>> +}
>> +
>> +#define CAL_CHECKSUM(pixel) (checksum + ((pixel) ^ xor_mask))
>> +static int verify_plane_checksum(const uint8_t *src, const int w, const int h, const int stride, const int ps,
>> +    const uint8_t *expected)
>> +{
>> +    uint32_t checksum = 0;
>> +
>> +    for (int y = 0; y < h; y++) {
>> +        for (int x = 0; x < w; x++) {
>> +            const int xor_mask = (x & 0xFF) ^ (y & 0xFF) ^ (x >> 8) ^ (y >> 8);
>> +            checksum = CAL_CHECKSUM(src[x << ps]);
>> +            if (ps)
>> +                checksum = CAL_CHECKSUM(src[(x << ps) + 1]);
>
> Why don't you use checksum += instead of using checksum in the
> CAL_CHECKSUM macro in a hardcoded manner?
>
>> +        }
>> +        src += stride;
>> +    }
>> +
>> +    if (checksum != *(uint32_t*)expected)
>> +        return AVERROR_INVALIDDATA;
>> +
>> +    return 0;
>> +}
>> +
>> +static const uint8_t *get_plane_hash(const H274SEIPictureHash *h, const int plane)
>> +{
>> +    if (!h->hash_type)
>> +        return h->md5[plane];
>> +    if (h->hash_type == 1)
>> +        return (uint8_t*)&h->crc[plane];
>> +    return (uint8_t*)&h->checksum[plane];
>> +}
>
> This function seems completely useless; you should better pass the
> proper expected value to the functions directly (by value for non-md5).
>
>> +
>> +enum {
>> +    HASH_MD5SUM,
>> +    HASH_CRC,
>> +    HASH_CHECKSUM,
>> +    HASH_LAST = HASH_CHECKSUM,
>> +};
>> +
>> +struct H274HashContext {
>> +    int type;
>> +    struct AVMD5 *ctx;
>> +};
>> +
>> +int ff_h274_hash_freep(H274HashContext **ctx)
>> +{
>> +    if (ctx && *ctx) {
>
> Don't check for ctx. Passing a NULL to a freep-function is insane.
>
>> +        H274HashContext *c = *ctx;
>> +        if (c->ctx)
>> +            av_free(c->ctx);
>> +        av_freep(ctx);
>> +    }
>> +    return 0;
>
> Why is this function returning anything?
>
>> +}
>> +
>> +int ff_h274_hash_init(H274HashContext **ctx, const int type)
>> +{
>> +    H274HashContext *c;
>> +
>> +    if (type > HASH_LAST || !ctx)
>> +        return AVERROR(EINVAL);
>> +
>> +    c = *ctx;
>> +    if (c) {
>> +        if (c->type != type) {
>> +            if (c->type == HASH_MD5SUM)
>> +                av_freep(&c->ctx);
>> +            c->type = type;
>> +        }
>> +    } else {
>> +        *ctx = c = av_mallocz(sizeof(H274HashContext));
>
> Why is this separately allocated?
>
>> +        if (!c)
>> +            return AVERROR(ENOMEM);
>> +        c->type = type;
>> +    }
>> +
>> +    if (type == HASH_MD5SUM && !c->ctx) {
>> +        c->ctx = av_md5_alloc();
>> +        if (!c->ctx)
>> +            return AVERROR(ENOMEM);
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +int ff_h274_hash_verify(H274HashContext *c, const H274SEIPictureHash *hash,
>> +    const AVFrame *frame, const int coded_width, const int coded_height)
>> +{
>> +    const AVPixFmtDescriptor *desc;
>> +    int err = 0;
>> +
>> +    if (!c || !hash || !frame)
>> +        return AVERROR(EINVAL);
>> +
>> +    if (c->type != hash->hash_type)
>> +        return AVERROR(EINVAL);
>> +
>> +    desc = av_pix_fmt_desc_get(frame->format);
>> +    if (!desc)
>> +        return AVERROR(EINVAL);
>> +
>> +    for (int i = 0; i < desc->nb_components; i++) {
>> +        const int w             = i ? (coded_width  >> desc->log2_chroma_w) : coded_width;
>> +        const int h             = i ? (coded_height >> desc->log2_chroma_h) : coded_height;
>> +        const int ps            = desc->comp[i].step - 1;
>> +        const uint8_t *expected = get_plane_hash(hash, i);
>> +        const uint8_t *src      = frame->data[i];
>> +        const int stride        = frame->linesize[i];
>> +
>> +        if (c->type == HASH_MD5SUM)
>> +            err = verify_plane_md5(c->ctx, src, w << ps, h, stride, expected);
>> +        else if (c->type == HASH_CRC)
>> +            err = verify_plane_crc(src, w << ps, h, stride, expected);
>> +        else if (c->type == HASH_CHECKSUM)
>> +            err = verify_plane_checksum(src, w, h, stride, ps, expected);
>> +        if (err < 0)
>> +            goto fail;
>> +    }
>> +
>> +fail:
>> +    return err;
>> +}
>> diff --git a/libavcodec/h274.h b/libavcodec/h274.h
>> index e1803edaf3..e2bb1aec55 100644
>> --- a/libavcodec/h274.h
>> +++ b/libavcodec/h274.h
>> @@ -64,6 +64,8 @@ int ff_h274_apply_film_grain(AVFrame *out, const AVFrame *in,
>>                               H274FilmGrainDatabase *db,
>>                               const AVFilmGrainParams *params);
>>
>> +typedef struct H274HashContext H274HashContext;
>> +
>>  typedef struct H274SEIPictureHash {
>>      int present;
>>      union {
>> @@ -74,4 +76,9 @@ typedef struct H274SEIPictureHash {
>>      uint8_t hash_type;
>>  } H274SEIPictureHash;
>>
>> +int ff_h274_hash_init(H274HashContext **c, int type);
>> +int ff_h274_hash_verify(H274HashContext *c, const H274SEIPictureHash *hash,
>> +    const AVFrame *frame, int coded_width, int coded_height);
>> +int ff_h274_hash_freep(H274HashContext **c);
>> +
>>  #endif /* AVCODEC_H274_H */

Hi Andreas,

Thanks for your reviews! They help a lot. I've updated the v2
patchset based on your comments. Would you help to review the
v2 patches?

Thanks,
Jianhua