Re: [FFmpeg-devel] [PATCH] avformat/framecrcenc: compute the checksum for side data

[James Almer <jamrial@gmail.com>]

On 4/30/2024 9:40 PM, Michael Niedermayer wrote:
> On Tue, Apr 30, 2024 at 08:29:07PM -0300, James Almer wrote:
>> On 4/30/2024 8:25 PM, Michael Niedermayer wrote:
>>> On Sun, Apr 28, 2024 at 12:43:50AM -0300, James Almer wrote:
>>>> On 4/27/2024 9:07 AM, Michael Niedermayer wrote:
>>>>> On Sat, Apr 27, 2024 at 12:44:18PM +0200, Andreas Rheinhardt wrote:
>>>>>> Michael Niedermayer:
>>>>>>> This allows detecting issues in side data related code, same as what
>>>>>>> framecrc does for before already for packet data itself.
>>>>>>>
>>>>>>> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
>>>>>>> ---
>>>>>>>     libavformat/framecrcenc.c                   |   76 +-
>>>>>>>     tests/ref/fate/autorotate                   |    2 +-
>>>>>>>     tests/ref/fate/cover-art-mp3-id3v2-remux    |    2 +-
>>>>>>>     tests/ref/fate/ffmpeg-bsf-input             |   10 +-
>>>>>>>     tests/ref/fate/force_key_frames-source      |  784 ++++++------
>>>>>>>     tests/ref/fate/force_key_frames-source-drop |   34 +-
>>>>>>>     tests/ref/fate/force_key_frames-source-dup  | 1224 +++++++++----------
>>>>>>>     tests/ref/fate/gapless-mp3                  |    6 +-
>>>>>>>     tests/ref/fate/h264_redundant_pps-side_data |    2 +-
>>>>>>>     tests/ref/fate/iamf-5_1-copy                |  208 ++--
>>>>>>>     tests/ref/fate/iamf-5_1-demux               |  208 ++--
>>>>>>>     tests/ref/fate/id3v2-priv-remux             |    2 +-
>>>>>>>     tests/ref/fate/matroska-hdr10-plus-remux    |    2 +-
>>>>>>>     tests/ref/fate/matroska-ogg-opus-remux      |    2 +-
>>>>>>>     tests/ref/fate/matroska-opus-remux          |    2 +-
>>>>>>>     tests/ref/fate/matroska-vp8-alpha-remux     |   14 +-
>>>>>>>     tests/ref/fate/mov-cover-image              |    2 +-
>>>>>>>     tests/ref/fate/segment-mp4-to-ts            |  250 ++--
>>>>>>>     tests/ref/fate/shortest                     |  100 +-
>>>>>>>     tests/ref/fate/webm-hdr10-plus-remux        |    2 +-
>>>>>>>     tests/ref/fate/webm-webvtt-remux            |   24 +-
>>>>>>>     21 files changed, 1513 insertions(+), 1443 deletions(-)
>>>>>>>
>>>>>>> diff --git a/libavformat/framecrcenc.c b/libavformat/framecrcenc.c
>>>>>>> index ce306a6c498..e71bfbd8777 100644
>>>>>>> --- a/libavformat/framecrcenc.c
>>>>>>> +++ b/libavformat/framecrcenc.c
>>>>>>> @@ -21,8 +21,10 @@
>>>>>>>     #include <inttypes.h>
>>>>>>> +#include "config.h"
>>>>>>>     #include "libavutil/adler32.h"
>>>>>>>     #include "libavutil/avstring.h"
>>>>>>> +#include "libavutil/intreadwrite.h"
>>>>>>>     #include "libavcodec/codec_id.h"
>>>>>>>     #include "libavcodec/codec_par.h"
>>>>>>> @@ -48,6 +50,17 @@ static int framecrc_write_header(struct AVFormatContext *s)
>>>>>>>         return ff_framehash_write_header(s);
>>>>>>>     }
>>>>>>> +static av_unused void inline bswap(char *buf, int offset, int size)
>>>>>>> +{
>>>>>>> +    if (size == 8) {
>>>>>>> +        uint64_t val = AV_RN64(buf + offset);
>>>>>>> +        AV_WN64(buf + offset, av_bswap64(val));
>>>>>>> +    } else if (size == 4) {
>>>>>>> +        uint32_t val = AV_RN32(buf + offset);
>>>>>>> +        AV_WN32(buf + offset, av_bswap32(val));
>>>>>>> +    }
>>>>>>> +}
>>>>>>> +
>>>>>>>     static int framecrc_write_packet(struct AVFormatContext *s, AVPacket *pkt)
>>>>>>>     {
>>>>>>>         uint32_t crc = av_adler32_update(0, pkt->data, pkt->size);
>>>>>>> @@ -58,11 +71,68 @@ static int framecrc_write_packet(struct AVFormatContext *s, AVPacket *pkt)
>>>>>>>         if (pkt->flags != AV_PKT_FLAG_KEY)
>>>>>>>             av_strlcatf(buf, sizeof(buf), ", F=0x%0X", pkt->flags);
>>>>>>>         if (pkt->side_data_elems) {
>>>>>>> +        int i;
>>>>>>
>>>>>> This change is wrong.
>>>>>>
>>>>>>>             av_strlcatf(buf, sizeof(buf), ", S=%d", pkt->side_data_elems);
>>>>>>> -        for (int i = 0; i < pkt->side_data_elems; i++) {
>>>>>>> -            av_strlcatf(buf, sizeof(buf), ", %8"SIZE_SPECIFIER,
>>>>>>> -                        pkt->side_data[i].size);
>>>>>>> +        for (i=0; i<pkt->side_data_elems; i++) {
>>>>>>> +            const AVPacketSideData *const sd = &pkt->side_data[i];
>>>>>>> +            const uint8_t *data = sd->data;
>>>>>>> +            uint32_t side_data_crc = 0;
>>>>>>> +
>>>>>>> +            switch (sd->type) {
>>>>>>> +#if HAVE_BIGENDIAN
>>>>>>> +                uint8_t bswap_buf[FFMAX(sizeof(AVCPBProperties),
>>>>>>> +                                        sizeof(AVProducerReferenceTime))];
>>>>>>> +            case AV_PKT_DATA_PALETTE:
>>>>>>> +            case AV_PKT_DATA_REPLAYGAIN:
>>>>>>> +            case AV_PKT_DATA_DISPLAYMATRIX:
>>>>>>> +            case AV_PKT_DATA_STEREO3D:
>>>>>>> +            case AV_PKT_DATA_AUDIO_SERVICE_TYPE:
>>>>>>> +            case AV_PKT_DATA_FALLBACK_TRACK:
>>>>>>> +            case AV_PKT_DATA_MASTERING_DISPLAY_METADATA:
>>>>>>> +            case AV_PKT_DATA_SPHERICAL:
>>>>>>> +            case AV_PKT_DATA_CONTENT_LIGHT_LEVEL:
>>>>>>> +            case AV_PKT_DATA_S12M_TIMECODE:
>>>>>>> +                for (size_t j = 0; j < sd->size / 4; j++) {
>>>>>>> +                    uint8_t buf[4];
>>>>>>> +                    AV_WL32(buf, AV_RB32(sd->data + 4 * j));
>>>>>>> +                    side_data_crc = av_adler32_update(side_data_crc, buf, 4);
>>>>>>> +                }
>>>>>>> +                break;
>>>>>>> +            case AV_PKT_DATA_CPB_PROPERTIES:
>>>>>>> +#define BSWAP(struct, field) bswap(bswap_buf, offsetof(struct, field), sizeof(((struct){0}).field))
>>>>>>> +                if (sd->size == sizeof(AVCPBProperties)) {
>>>>>>> +                    memcpy(bswap_buf, sd->data, sizeof(AVCPBProperties));
>>>>>>> +                    data = bswap_buf;
>>>>>>> +                    BSWAP(AVCPBProperties, max_bitrate);
>>>>>>> +                    BSWAP(AVCPBProperties, min_bitrate);
>>>>>>> +                    BSWAP(AVCPBProperties, avg_bitrate);
>>>>>>> +                    BSWAP(AVCPBProperties, buffer_size);
>>>>>>> +                    BSWAP(AVCPBProperties, vbv_delay);
>>>>>>> +                }
>>>>>>> +                goto pod;
>>>>>>> +            case AV_PKT_DATA_PRFT:
>>>>>>> +                if (sd->size == sizeof(AVProducerReferenceTime)) {
>>>>>>> +                    memcpy(bswap_buf, sd->data, sizeof(AVProducerReferenceTime));
>>>>>>> +                    data = bswap_buf;
>>>>>>> +                    BSWAP(AVProducerReferenceTime, wallclock);
>>>>>>> +                    BSWAP(AVProducerReferenceTime, flags);
>>>>>>> +                }
>>>>>>> +                goto pod;
>>>>>>> +            pod:
>>>>>>> +#endif
>>>>>>> +
>>>>>>> +            default:
>>>>>>> +                side_data_crc = av_adler32_update(0, data, sd->size);
>>>>>>> +                break;
>>>>>>> +            case AV_PKT_DATA_IAMF_MIX_GAIN_PARAM:
>>>>>>> +            case AV_PKT_DATA_IAMF_DEMIXING_INFO_PARAM:
>>>>>>> +            case AV_PKT_DATA_IAMF_RECON_GAIN_INFO_PARAM:
>>>>>>> +                side_data_crc = 0;
>>>>>>> +            }
>>>>>>> +
>>>>>>> +            av_strlcatf(buf, sizeof(buf), ", %8"SIZE_SPECIFIER", 0x%08"PRIx32,
>>>>>>> +                        pkt->side_data[i].size, side_data_crc);
>>>>>>>             }
>>>>>>>         }
>>>>>>>         av_strlcatf(buf, sizeof(buf), "\n");
>>>>>>
>>>>>> You should mention that you are basically reverting
>>>>>> c6ae560a18d67b9ddaa25a0338b7fb55e3312e57.
>>>>>
>>>>> right, i didnt keep track of this as i just needed this locally
>>>>> for testing to be possible and at the time didnt expect to
>>>>> submit this to ffmpeg. But now 3 years later, it seems to make
>>>>> sense to see if people want this maybe.
>>>>>
>>>>> To test side data, it IS needed to well test side data.
>>>>> But if people still want to not test side data in FFmpeg git.
>>>>> I can continue to be the only one testing side data :)
>>>>>
>>>>> ill repost it with a reference to c6ae560a18d67b9ddaa25a0338b7fb55e3312e57
>>>>> and without the int i change, i did miss that.
>>>>
>>>> I'm not against adding checksum for side data if it can be ensured it will
>>>> be the same on both little and big endian, 32bit and 64bit,
>>>
>>> If side data uses types that have a size that is platform dependant
>>> (except pointers). Thats probably a mistake that should be corrected
>>> on the next ABI bump.
>>
>> size_t is used for buffer offsets on the IAMF side data types. I guess it
>> could be changed to uint32_t.
> 
> i think uint32 would have been better, yes

It will probably not be enough anyway. There's alignment at play too.
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