Michael Niedermayer:
> On Sun, Jul 05, 2020 at 12:54:53AM +0200, Jan Engelhardt wrote:
>> Greetings.
>>
>>
>> Between ffmpeg-4.2.3 and ffmpeg-4.3, struct AVCodecContext,
>> publicly exposed through /usr/include, has been changed thus:
>>
>> --- avcodec.h 2020-06-11 11:45:16.000000000 +0200
>> +++ avcodec.h 2020-07-01 03:45:24.000000000 +0200
>> @@ -3370,6 +2334,24 @@ typedef struct AVCodecContext {
>> * - encoding: unused
>> */
>> int discard_damaged_percentage;
>> +
>> + /**
>> + * The number of samples per frame to maximally accept.
>> + *
>> + * - decoding: set by user
>> + * - encoding: set by user
>> + */
>> + int64_t max_samples;
>> +
>> + /**
>> + * Bit set of AV_CODEC_EXPORT_DATA_* flags, which affects the kind of
>> + * metadata exported in frame, packet, or coded stream side data by
>> + * decoders and encoders.
>> + *
>> + * - decoding: set by user
>> + * - encoding: set by user
>> + */
>> + int export_side_data;
>> } AVCodecContext;
>>
>> #if FF_API_CODEC_GET_SET
>>
>>
>> Second, struct AVDCT, which is publicly exposed through /usr/include, has
>> been
>> changed:
>>
>> --- avdct.h 2020-06-11 11:45:16.000000000 +0200
>> +++ avdct.h 2020-07-01 03:45:24.000000000 +0200
>> @@ -67,6 +67,10 @@ typedef struct AVDCT {
>> ptrdiff_t line_size);
>>
>> int bits_per_sample;
>> +
>> + void (*get_pixels_unaligned)(int16_t *block /* align 16 */,
>> + const uint8_t *pixels,
>> + ptrdiff_t line_size);
>> } AVDCT;
>>
>> /**
>>
>>
>> The abidiff(1) utility confirms this situation such:
>>
>> $ abidiff
>> b42/usr/lib/debug/usr/lib64/libavcodec.so.58.54.100-4.2.3-1.1.x86_64.debug \
>>
>> b43/usr/lib/debug/usr/lib64/libavcodec.so.58.91.100-4.3-136.2.x86_64.debug
>>
>> [...] in pointed to type 'struct AVCodecContext' at avcodec.h:526:1:
>> type size changed from 8448 to 8576 (in bits)
>> [...]
>> underlying type 'struct AVDCT' at avdct.h:29:1 changed:
>> type size changed from 896 to 960 (in bits)
>>
>>
>> These struct changes constitute an ABI break, and ABI breaks require SO
>> version
>> bumps, but which was not done for 4.3. This is bad.
>
> Quoting the AVCodecContext documentation from FFmpeg 4.2.3
>
> /**
> * main external API structure.
> * New fields can be added to the end with minor version bumps.
> * Removal, reordering and changes to existing fields require a major
> * version bump.
> * You can use AVOptions (av_opt* / av_set/get*()) to access these fields
> from user
> * applications.
> * The name string for AVOptions options matches the associated command line
> * parameter name and can be found in libavcodec/options_table.h
> * The AVOption/command line parameter names differ in some cases from the C
> * structure field names for historic reasons or brevity.
> * sizeof(AVCodecContext) must not be used outside libav*.
> */
> typedef struct AVCodecContext {
>
>
>>
>> A user has summarily reported crashes through {not a proper bug reporting
>> medium} already.
>> https://build.opensuse.org/package/show/multimedia:libs/ffmpeg-4
>
> have you identified what exactly causes the crashes ?
>
This is the user report:
"Unfortunately, this version is binary incompatible to 4.2.3 in some
aspects. Chromium crashes when accessing some sites, e.g.
https://www.xometry.com/ and push the quote button. Blender cannot
export PNG files anymore."
This crash is due to Chromium using av_max_alloc in an undocumented way;
more exactly, the Chromium FFmpeg fork changes the allocation functions
so that if max_alloc_size is zero, the limit is completely disabled; and
of course it also sets the limit to zero. Up until 4.2, this worked with
a normal FFmpeg, because FFmpeg didn't max_alloc_size as is, but instead
max_alloc_size - 32. But since 731c77589841c02e014aa7f8285dcfc8b20f2ee5
this is no longer so. The relevant chromium bug is at
https://bugs.chromium.org/p/chromium/issues/detail?id=1095962
I don't know what the issue with Blender is.
- Andreas
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
