Message ID | 20201207035609.546350-1-andreas.rheinhardt@gmail.com |
---|---|
State | Accepted |
Commit | 0dac317ba31cd10e9df26722ac96adc3f6ef3eb3 |
Headers | show |
Series | [FFmpeg-devel,v3] avformat/framecrcenc: Make side-data checksums endian-independent | expand |
Context | Check | Description |
---|---|---|
andriy/x86 | warning | Failed to apply patch |
IMO checksumming side data contents is a bad idea and should not be done at all. It's supposed to be an in-memory representation, which is inherently platform-dependent - besides endianness there are potential issues with padding or type sizes. If we want to test side data, we should use some other mechanism for it (e.g. ffprobe).
Anton Khirnov (12020-12-13): > IMO checksumming side data contents is a bad idea and should not be done > at all. It's supposed to be an in-memory representation, which is > inherently platform-dependent - besides endianness there are potential > issues with padding or type sizes. If we want to test side data, we > should use some other mechanism for it (e.g. ffprobe). I agree with this take, but I think you are only grazing the tip of the iceberg here. I think than whenever we add a simple type (enum or structure) for use as a side-data structure, frame property or similar, we should add a set of function to perform the basic operations, with standardized names and prototype: freeing, copy/cloning, printing, possibly checksumming, etc. Do you not agree it would be a worthy discipline? (Of course, if we agree on it, we need to revisit existing types to give them these functions too.) Regards,
On Wed, Dec 16, 2020 at 08:09:29PM +0100, Nicolas George wrote: > Anton Khirnov (12020-12-13): > > IMO checksumming side data contents is a bad idea and should not be done > > at all. It's supposed to be an in-memory representation, which is > > inherently platform-dependent - besides endianness there are potential > > issues with padding or type sizes. If we want to test side data, we > > should use some other mechanism for it (e.g. ffprobe). > > I agree with this take, but I think you are only grazing the tip of the > iceberg here. > > I think than whenever we add a simple type (enum or structure) for use > as a side-data structure, frame property or similar, we should add a set > of function to perform the basic operations, with standardized names and > prototype: freeing, copy/cloning, printing, possibly checksumming, etc. > > Do you not agree it would be a worthy discipline? > > (Of course, if we agree on it, we need to revisit existing types to give > them these functions too.) Maybe code which can generically serialize side data into a bit exact bytestream would be usefull. checksumming would be a one time implementation on top of this not a per side data one. Also transmitting this data accross a network or other would be trivial Thanks [...]
Michael Niedermayer (12020-12-17): > Maybe code which can generically serialize side data into a bit exact > bytestream would be usefull. checksumming would be a one time implementation > on top of this not a per side data one. > Also transmitting this data accross a network or other would be trivial Yes, serializing to a bytestream is probably one of the standardized function we need for every type. And indeed, if we have it we do need checksumming. Regards,
diff --git a/libavformat/framecrcenc.c b/libavformat/framecrcenc.c index f7c48779a0..1fbe4aa4ee 100644 --- a/libavformat/framecrcenc.c +++ b/libavformat/framecrcenc.c @@ -21,9 +21,11 @@ #include <inttypes.h> +#include "config.h" #include "libavutil/adler32.h" #include "libavutil/avstring.h" #include "libavutil/intreadwrite.h" +#include "libavcodec/avcodec.h" #include "avformat.h" #include "internal.h" @@ -43,6 +45,17 @@ 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); @@ -58,17 +71,53 @@ static int framecrc_write_packet(struct AVFormatContext *s, AVPacket *pkt) 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; - if (HAVE_BIGENDIAN && AV_PKT_DATA_PALETTE == pkt->side_data[i].type) { + + 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 (int 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); } - } else { - side_data_crc = av_adler32_update(0, - pkt->side_data[i].data, - pkt->side_data[i].size); + 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); } av_strlcatf(buf, sizeof(buf), ", %8d, 0x%08"PRIx32, pkt->side_data[i].size, side_data_crc); }