James Almer:
> On 4/30/2020 3:50 PM, Andreas Rheinhardt wrote:
>> James Almer:
>>> Fixes ticket #8622
>>>
>>> Signed-off-by: James Almer <jamr...@gmail.com>
>>> ---
>>> In writing scenarios, it will now ensure bit_equal_to_one is also always
>>> written when currently defined extension data (like in Buffering Period) is
>>> present, and not just when unknown extension data is.
>>>
>>> libavcodec/cbs_h2645.c | 1 +
>>> libavcodec/cbs_h265.h | 1 +
>>> libavcodec/cbs_h265_syntax_template.c | 71 +++++++++++++++++++++++++--
>>> 3 files changed, 68 insertions(+), 5 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> ---
>>> a/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..45838467b7 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, end_position;
>>> + int more_data = !!current->extension_data.bit_length;
>>
>> If I am not mistaken, then more_data is a write-only variable when
>> reading. Better add av_unused or it might lead to compiler warnings.
>> (You might even move the definition of more_data into the ifdef block
>> below and only initialize it during writing.)
>
> more_data is used as an argument when calling SEI messages using the new
> SEI_TYPE_E() macro, so that should prevent such warnings. I at least
> haven't seen any in my tests.
>
But none of these functions will actually use it during reading and
therefore a smart compiler (maybe a future one) might find out that this
variable is write-only.
- Andreas
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