[FFmpeg-devel] [PATCH 2/2] avformat/hnm: Only keep and parse what is needed later

[Andreas Rheinhardt]

Paul B Mahol:
> ok if fate passed and it is covered.
> 
> On 3/21/20, Andreas Rheinhardt <andreas.rheinhardt at gmail.com> wrote:
>> The hnm demuxer's context struct contained lots of fields that are
>> write-only variables or that are not used outside of parsing the header
>> and that can therefore be replaced by local variables of hnm_read_header().
>> This commit removes all of these from the context; the second type has
>> been replaced by local variables.
>>
>> An AVPacket (that was initialized when reading the header and for which
>> dead code to unreference it existed in hnm_read_close()) is among the
>> removed things. Removing it allowed to remove hnm_read_close()
>> altogether and also removes another instance of usage of sizeof(AVPacket).
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>>  libavformat/hnm.c | 63 +++++++++--------------------------------------
>>  1 file changed, 12 insertions(+), 51 deletions(-)
>>
>> diff --git a/libavformat/hnm.c b/libavformat/hnm.c
>> index 31221553a4..f06add5cf8 100644
>> --- a/libavformat/hnm.c
>> +++ b/libavformat/hnm.c
>> @@ -37,19 +37,9 @@
>>  #define HNM4_CHUNK_ID_SD 17491
>>
>>  typedef struct Hnm4DemuxContext {
>> -    uint8_t version;
>> -    uint16_t width;
>> -    uint16_t height;
>> -    uint32_t filesize;
>>      uint32_t frames;
>> -    uint32_t taboffset;
>> -    uint16_t bits;
>> -    uint16_t channels;
>> -    uint32_t framesize;
>>      uint32_t currentframe;
>> -    int64_t pts;
>>      uint32_t superchunk_remaining;
>> -    AVPacket vpkt;
>>  } Hnm4DemuxContext;
>>
>>  static int hnm_probe(const AVProbeData *p)
>> @@ -69,55 +59,37 @@ static int hnm_read_header(AVFormatContext *s)
>>  {
>>      Hnm4DemuxContext *hnm = s->priv_data;
>>      AVIOContext *pb = s->pb;
>> +    unsigned width, height;
>>      AVStream *vst;
>>      int ret;
>>
>> -    /* default context members */
>> -    hnm->pts = 0;
>> -    av_init_packet(&hnm->vpkt);
>> -    hnm->vpkt.data = NULL;
>> -    hnm->vpkt.size = 0;
>> -
>> -    hnm->superchunk_remaining = 0;
>> -
>>      avio_skip(pb, 8);
>> -    hnm->width     = avio_rl16(pb);
>> -    hnm->height    = avio_rl16(pb);
>> -    hnm->filesize  = avio_rl32(pb);
>> +    width          = avio_rl16(pb);
>> +    height         = avio_rl16(pb);
>> +    avio_rl32(pb); // filesize
>>      hnm->frames    = avio_rl32(pb);
>> -    hnm->taboffset = avio_rl32(pb);
>> -    hnm->bits      = avio_rl16(pb);
>> -    hnm->channels  = avio_rl16(pb);
>> -    hnm->framesize = avio_rl32(pb);
>> -    avio_skip(pb, 32);
>> +    avio_skip(pb, 44);
>>
>> -    hnm->currentframe = 0;
>> -
>> -    if (hnm->width  < 256 || hnm->width  > 640 ||
>> -        hnm->height < 150 || hnm->height > 480) {
>> +    if (width  < 256 || width  > 640 ||
>> +        height < 150 || height > 480) {
>>          av_log(s, AV_LOG_ERROR,
>> -               "invalid resolution: %ux%u\n", hnm->width, hnm->height);
>> +               "invalid resolution: %ux%u\n", width, height);
>>          return AVERROR_INVALIDDATA;
>>      }
>>
>> -    // TODO: find a better way to detect HNM4A
>> -    if (hnm->width == 640)
>> -        hnm->version = 0x4a;
>> -    else
>> -        hnm->version = 0x40;
>> -
>>      if (!(vst = avformat_new_stream(s, NULL)))
>>          return AVERROR(ENOMEM);
>>
>>      vst->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
>>      vst->codecpar->codec_id   = AV_CODEC_ID_HNM4_VIDEO;
>>      vst->codecpar->codec_tag  = 0;
>> -    vst->codecpar->width      = hnm->width;
>> -    vst->codecpar->height     = hnm->height;
>> +    vst->codecpar->width      = width;
>> +    vst->codecpar->height     = height;
>>      if ((ret = ff_alloc_extradata(vst->codecpar, 1)) < 0)
>>          return ret;
>>
>> -    vst->codecpar->extradata[0] = hnm->version;
>> +    // TODO: find a better way to detect HNM4A
>> +    vst->codecpar->extradata[0] = width == 640 ? 0x4a : 0x40;
>>
>>      vst->start_time = 0;
>>
>> @@ -186,16 +158,6 @@ static int hnm_read_packet(AVFormatContext *s, AVPacket
>> *pkt)
>>      return ret;
>>  }
>>
>> -static int hnm_read_close(AVFormatContext *s)
>> -{
>> -    Hnm4DemuxContext *hnm = s->priv_data;
>> -
>> -    if (hnm->vpkt.size > 0)
>> -        av_packet_unref(&hnm->vpkt);
>> -
>> -    return 0;
>> -}
>> -
>>  AVInputFormat ff_hnm_demuxer = {
>>      .name           = "hnm",
>>      .long_name      = NULL_IF_CONFIG_SMALL("Cryo HNM v4"),
>> @@ -203,6 +165,5 @@ AVInputFormat ff_hnm_demuxer = {
>>      .read_probe     = hnm_probe,
>>      .read_header    = hnm_read_header,
>>      .read_packet    = hnm_read_packet,
>> -    .read_close     = hnm_read_close,
>>      .flags          = AVFMT_NO_BYTE_SEEK | AVFMT_NOGENSEARCH |
>> AVFMT_NOBINSEARCH
>>  };
>> --
>> 2.20.1

Thanks, applied.

- Andreas