[FFmpeg-devel] [PATCH] avformat/avc: write the missing bits in the AVC Decoder Configuration Box

[James Almer]

On 11/26/2019 10:57 AM, Andreas Rheinhardt wrote:
> On Tue, Nov 26, 2019 at 2:07 PM James Almer <jamrial at gmail.com> wrote:
> 
>> Signed-off-by: James Almer <jamrial at gmail.com>
>> ---
>>  libavformat/avc.c | 38 +++++++++++++++++++++++++++++++++-----
>>  libavformat/avc.h |  1 +
>>  2 files changed, 34 insertions(+), 5 deletions(-)
>>
>> diff --git a/libavformat/avc.c b/libavformat/avc.c
>> index a041e84357..9bd215c07f 100644
>> --- a/libavformat/avc.c
>> +++ b/libavformat/avc.c
>> @@ -107,11 +107,11 @@ int ff_avc_parse_nal_units_buf(const uint8_t
>> *buf_in, uint8_t **buf, int *size)
>>
>>  int ff_isom_write_avcc(AVIOContext *pb, const uint8_t *data, int len)
>>  {
>> -    AVIOContext *sps_pb = NULL, *pps_pb = NULL;
>> +    AVIOContext *sps_pb = NULL, *pps_pb = NULL, *sps_ext_pb = NULL;
>>      uint8_t *buf = NULL, *end, *start = NULL;
>> -    uint8_t *sps = NULL, *pps = NULL;
>> -    uint32_t sps_size = 0, pps_size = 0;
>> -    int ret, nb_sps = 0, nb_pps = 0;
>> +    uint8_t *sps = NULL, *pps = NULL, *sps_ext = NULL;
>> +    uint32_t sps_size = 0, pps_size = 0, sps_ext_size = 0;
>> +    int ret, nb_sps = 0, nb_pps = 0, nb_sps_ext = 0;
>>
>>      if (len <= 6)
>>          return AVERROR_INVALIDDATA;
>> @@ -133,6 +133,9 @@ int ff_isom_write_avcc(AVIOContext *pb, const uint8_t
>> *data, int len)
>>      if (ret < 0)
>>          goto fail;
>>      ret = avio_open_dyn_buf(&pps_pb);
>> +    if (ret < 0)
>> +        goto fail;
>> +    ret = avio_open_dyn_buf(&sps_ext_pb);
>>      if (ret < 0)
>>          goto fail;
>>
>> @@ -160,12 +163,21 @@ int ff_isom_write_avcc(AVIOContext *pb, const
>> uint8_t *data, int len)
>>              }
>>              avio_wb16(pps_pb, size);
>>              avio_write(pps_pb, buf, size);
>> +        } else if (nal_type == 13) { /* SPS_EXT */
>> +            nb_sps_ext++;
>> +            if (size > UINT16_MAX || nb_sps_ext >= 256) {
>> +                ret = AVERROR_INVALIDDATA;
>> +                goto fail;
>> +            }
>> +            avio_wb16(sps_ext_pb, size);
>> +            avio_write(sps_ext_pb, buf, size);
>>          }
>>
>>          buf += size;
>>      }
>>      sps_size = avio_close_dyn_buf(sps_pb, &sps);
>>      pps_size = avio_close_dyn_buf(pps_pb, &pps);
>> +    sps_ext_size = avio_close_dyn_buf(sps_ext_pb, &sps_ext);
>>
>>      if (sps_size < 6 || !pps_size) {
>>          ret = AVERROR_INVALIDDATA;
>> @@ -183,13 +195,29 @@ int ff_isom_write_avcc(AVIOContext *pb, const
>> uint8_t *data, int len)
>>      avio_w8(pb, nb_pps); /* number of pps */
>>      avio_write(pb, pps, pps_size);
>>
>> +    if (sps[3] != 66 && sps[3] != 77 && sps[3] != 88) {
>> +        H264SequenceParameterSet *seq = ff_avc_decode_sps(sps, sps_size);
>> +        if (!seq)
>> +            goto fail;
>> +        avio_w8(pb, 0xfc | seq->chroma_format_idc); /* 6 bits reserved
>> (111111) + chroma_format_idc */
>> +        avio_w8(pb, 0xf8 | seq->bit_depth_luma - 8); /* 5 bits reserved
>> (11111) + bit_depth_luma_minus8 */
>> +        avio_w8(pb, 0xf8 | seq->bit_depth_chroma - 8); /* 5 bits reserved
>> (11111) + bit_depth_chroma_minus8 */
>> +        avio_w8(pb, nb_sps_ext); /* number of sps ext */
>> +        if (nb_sps_ext)
>> +            avio_write(pb, sps_ext, sps_ext_size);
>> +        av_free(seq);
>> +    }
>> +
>>  fail:
>>      if (!sps)
>>          avio_close_dyn_buf(sps_pb, &sps);
>>      if (!pps)
>>          avio_close_dyn_buf(pps_pb, &pps);
>> +    if (!sps_ext)
>> +        avio_close_dyn_buf(sps_ext_pb, &sps_ext);
>>
> 
> I don't like how these buffers are freed. How about the following approach:
> You don't close the dynamic buffer above; instead you just call
> avio_get_dyn_buf(). And here on fail you use ffio_free_dyn_buf()
> unconditionally instead of these combinations of avio_close_dyn_buf() and
> av_free().

Ok, will change that and apply this soon.