On 5/3/2020 7:22 PM, Mark Thompson wrote:
> On 03/05/2020 16:55, James Almer wrote:
>> On 5/3/2020 12:39 PM, Mark Thompson wrote:
>>> On 30/04/2020 22:50, James Almer wrote:
>>>> Fixes ticket #8622
>>>>
>>>> Signed-off-by: James Almer <jamr...@gmail.com>
>>>> ---
>>>> libavcodec/cbs_h2645.c | 1 +
>>>> libavcodec/cbs_h265.h | 1 +
>>>> libavcodec/cbs_h265_syntax_template.c | 85 +++++++++++++++++++++------
>>>> 3 files changed, 70 insertions(+), 17 deletions(-)
>>>>
>>>> diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
>>>> index 095e449ddc..b432921ecc 100644
>>>> --- a/libavcodec/cbs_h2645.c
>>>> +++ b/libavcodec/cbs_h2645.c
>>>> @@ -553,6 +553,7 @@ static void
>>>> cbs_h265_free_sei_payload(H265RawSEIPayload *payload)
>>>> av_buffer_unref(&payload->payload.other.data_ref);
>>>> break;
>>>> }
>>>> + av_buffer_unref(&payload->extension_data.data_ref);
>>>> }
>>>>
>>>> static void cbs_h265_free_sei(void *opaque, uint8_t *content)
>>>> diff --git a/libavcodec/cbs_h265.h b/libavcodec/cbs_h265.h
>>>> index 2c1e153ad9..73897f77a4 100644
>>>> --- a/libavcodec/cbs_h265.h
>>>> +++ b/libavcodec/cbs_h265.h
>>>> @@ -715,6 +715,7 @@ typedef struct H265RawSEIPayload {
>>>> AVBufferRef *data_ref;
>>>> } other;
>>>> } payload;
>>>> + H265RawExtensionData extension_data;
>>>> } H265RawSEIPayload;
>>>>
>>>> typedef struct H265RawSEI {
>>>> diff --git a/libavcodec/cbs_h265_syntax_template.c
>>>> b/libavcodec/cbs_h265_syntax_template.c
>>>> index ed08b06e9c..d3ac618db6 100644
>>>> --- a/libavcodec/cbs_h265_syntax_template.c
>>>> +++ b/libavcodec/cbs_h265_syntax_template.c
>>>> @@ -1564,7 +1564,8 @@ static int
>>>> FUNC(slice_segment_header)(CodedBitstreamContext *ctx, RWContext *rw,
>>>>
>>>> static int FUNC(sei_buffering_period)(CodedBitstreamContext *ctx,
>>>> RWContext *rw,
>>>> H265RawSEIBufferingPeriod *current,
>>>> - uint32_t *payload_size)
>>>> + uint32_t *payload_size,
>>>> + int *more_data)
>>>> {
>>>> CodedBitstreamH265Context *h265 = ctx->priv_data;
>>>> const H265RawSPS *sps;
>>>> @@ -1658,8 +1659,15 @@ static int
>>>> FUNC(sei_buffering_period)(CodedBitstreamContext *ctx, RWContext *rw,
>>>> else
>>>> infer(use_alt_cpb_params_flag, 0);
>>>> #else
>>>> - if (current->use_alt_cpb_params_flag)
>>>> + // If unknown extension data exists, then use_alt_cpb_params_flag is
>>>> + // coded in the bitstream and must be written even if it's 0.
>>>> + if (current->use_alt_cpb_params_flag || *more_data) {
>>>> flag(use_alt_cpb_params_flag);
>>>> + // Ensure this bit is not the last in the payload by making the
>>>> + // more_data_in_payload() check evaluate to true, so it may not
>>>> + // be mistaken as something else by decoders.
>>>> + *more_data = 1;
>>>> + }
>>>> #endif
>>>>
>>>> return 0;
>>>> @@ -2057,11 +2065,48 @@ static int
>>>> FUNC(sei_alpha_channel_info)(CodedBitstreamContext *ctx,
>>>> return 0;
>>>> }
>>>>
>>>> +static int FUNC(payload_extension)(CodedBitstreamContext *ctx, RWContext
>>>> *rw,
>>>> + H265RawExtensionData *current,
>>>> uint32_t payload_size,
>>>> + int cur_pos)
>>>> +{
>>>> + int err;
>>>> + size_t byte_length, k;
>>>> +
>>>> +#ifdef READ
>>>> + GetBitContext tmp;
>>>> + int bits_left, payload_zero_bits;
>>>> +
>>>> + if (!cbs_h265_payload_extension_present(rw, payload_size, cur_pos))
>>>> + return 0;
>>>> +
>>>> + bits_left = 8 * payload_size - cur_pos;
>>>> + tmp = *rw;
>>>> + if (bits_left > 8)
>>>> + skip_bits_long(&tmp, bits_left - 8);
>>>> + payload_zero_bits = get_bits(&tmp, FFMIN(bits_left, 8));
>>>> + if (!payload_zero_bits)
>>>> + return AVERROR_INVALIDDATA;
>>>> + payload_zero_bits = ff_ctz(payload_zero_bits);
>>>> + current->bit_length = bits_left - payload_zero_bits - 1;
>>>> + allocate(current->data, (current->bit_length + 7) / 8);
>>>> +#endif
>>>> +
>>>> + byte_length = (current->bit_length + 7) / 8;
>>>> + for (k = 0; k < byte_length; k++) {
>>>> + int length = FFMIN(current->bit_length - k * 8, 8);
>>>> + xu(length, reserved_payload_extension_data, current->data[k],
>>>> + 0, MAX_UINT_BITS(length), 0);
>>>> + }
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> static int FUNC(sei_payload)(CodedBitstreamContext *ctx, RWContext *rw,
>>>> H265RawSEIPayload *current, int prefix)
>>>> {
>>>> int err, i;
>>>> - int start_position, end_position;
>>>> + int start_position, current_position;
>>>> + int more_data = !!current->extension_data.bit_length;
>>>>
>>>> #ifdef READ
>>>> start_position = get_bits_count(rw);
>>>> @@ -2093,8 +2138,15 @@ static int FUNC(sei_payload)(CodedBitstreamContext
>>>> *ctx, RWContext *rw,
>>>> CHECK(FUNC(sei_ ## name)(ctx, rw, ¤t->payload.name, \
>>>> ¤t->payload_size)); \
>>>> break
>>>> +#define SEI_TYPE_E(type, prefix_valid, suffix_valid, name) \
>>>> + case HEVC_SEI_TYPE_ ## type: \
>>>> + SEI_TYPE_CHECK_VALID(name, prefix_valid, suffix_valid); \
>>>> + CHECK(FUNC(sei_ ## name)(ctx, rw, ¤t->payload.name, \
>>>> + ¤t->payload_size, \
>>>> + &more_data)); \
>>>> + break
>>>>
>>>> - SEI_TYPE_S(BUFFERING_PERIOD, 1, 0, buffering_period);
>>>> + SEI_TYPE_E(BUFFERING_PERIOD, 1, 0, buffering_period);
>>>> SEI_TYPE_N(PICTURE_TIMING, 1, 0, pic_timing);
>>>> SEI_TYPE_N(PAN_SCAN_RECT, 1, 0, pan_scan_rect);
>>>> SEI_TYPE_S(USER_DATA_REGISTERED_ITU_T_T35,
>>>> @@ -2125,24 +2177,23 @@ static int FUNC(sei_payload)(CodedBitstreamContext
>>>> *ctx, RWContext *rw,
>>>> }
>>>> }
>>>>
>>>> - if (byte_alignment(rw)) {
>>>> + // more_data_in_payload()
>>>> +#ifdef READ
>>>> + current_position = get_bits_count(rw) - start_position;
>>>> + if (current_position < 8 * current->payload_size) {
>>>> +#else
>>>> + current_position = put_bits_count(rw) - start_position;
>>>> + if (byte_alignment(rw) || more_data) {
>>>> +#endif
>
> Maybe put the { outside the #if so that it matches cleanly?
>
>>>> + CHECK(FUNC(payload_extension)(ctx, rw, ¤t->extension_data,
>>>> + current->payload_size,
>>>> current_position));
>>>> fixed(1, bit_equal_to_one, 1);
>>>> while (byte_alignment(rw))
>>>> fixed(1, bit_equal_to_zero, 0);
>>>> }
>>>>
>>>> -#ifdef READ
>>>> - end_position = get_bits_count(rw);
>>>> - if (end_position < start_position + 8 * current->payload_size) {
>>>> - av_log(ctx->log_ctx, AV_LOG_ERROR, "Incorrect SEI payload length:
>>>> "
>>>> - "header %"PRIu32" bits, actually %d bits.\n",
>>>> - 8 * current->payload_size,
>>>> - end_position - start_position);
>>>> - return AVERROR_INVALIDDATA;
>>>> - }
>>>> -#else
>>>> - end_position = put_bits_count(rw);
>>>> - current->payload_size = (end_position - start_position) >> 3;
>>>> +#ifdef WRITE
>>>> + current->payload_size = (put_bits_count(rw) - start_position) >> 3;
>>>> #endif
>>>>
>>>> return 0;
>>>>
>>>
>>> Could we avoid some of the extra code here by making a new GetBitContext in
>>> sei_payload containing only the payload bits and passing that to the
>>> per-type SEI reading functions? The functions themselves would know
>>> whether any additional bits are present purely from get_bits_left() -
>>> buffering_period could then be a normal SEI_TYPE_N and the code in it would
>>> be simpler.
>>
>> The SEI_TYPE_E macro is for the writing scenario, where we can't always
>> know until the message is finished if we have to write extra bits or not.
>> For Buffering Period, if we have some extra payload data that we need to
>> pass through, then use_alt_cpb_params_flag must be written, be it 1 or
>> 0. If we don't have extra payload data that we need to pass through, but
>> we wrote use_alt_cpb_params_flag because it was 1, then the calling
>> function cbs_h265_write_sei_payload() needs to know this happened so it
>> may always write a bit_equal_to_1 and potentially also a bunch of
>> bit_equal_to_0, even if after use_alt_cpb_params_flag we were byte
>> aligned, to ensure decoders compliant with any spec revision will not
>> mistake it for something else.
>>
>> Making each SEI message have its own GetBitContext in a reading scenario
>> will not make a difference for the above.
>
> Ok, that makes sense. (I was hoping that we might be able to make the ugly
> SEI code cleaner, but apparently not today. Oh well.)
>
> LGTM.
>
> Thanks,
>
> - Mark
Pushed, thanks.
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