On Sun, Sep 10, 2023 at 2:18 PM Andreas Rheinhardt < andreas.rheinha...@outlook.com> wrote:
> Paul B Mahol: > > On Sun, Sep 10, 2023 at 2:06 PM Andreas Rheinhardt < > > andreas.rheinha...@outlook.com> wrote: > > > >> Paul B Mahol: > >>> On Sun, Sep 10, 2023 at 1:59 PM Andreas Rheinhardt < > >>> andreas.rheinha...@outlook.com> wrote: > >>> > >>>> Paul B Mahol: > >>>>> On Wed, Sep 6, 2023 at 1:30 PM Andreas Rheinhardt < > >>>>> andreas.rheinha...@outlook.com> wrote: > >>>>> > >>>>>> Paul B Mahol: > >>>>>>> On Wed, Sep 6, 2023 at 11:26 AM Andreas Rheinhardt < > >>>>>>> andreas.rheinha...@outlook.com> wrote: > >>>>>>> > >>>>>>>> Paul B Mahol: > >>>>>>>>> > >>>>>>>>> + chunk_type = avio_rb32(pb); > >>>>>>>>> + chunk_size = avio_rb32(pb); > >>>>>>>> > >>>>>>>> You are not checking whether the chunk here exceeds its containing > >>>>>> chunk. > >>>>>>>> > >>>>>>>>> > >>>>>>>>> + av_fast_malloc(&usm->header, &usm->header_size, > >>>>>>>>> + chunk_size + AV_INPUT_BUFFER_PADDING_SIZE); > >>>>>>>>> + if (!usm->header) > >>>>>>>>> + return AVERROR(ENOMEM); > >>>>>>>> > >>>>>>>> The bytestream2 API does not rely on the buffer being padded at > all. > >>>>>>>> > >>>>>>>>> > >>>>>>>>> + bytestream2_skip(&sgb, string_offset); > >>>>>>>> > >>>>>>>> This is unnecessary, because you seek with an absolute offset > >> lateron > >>>>>>>> anyway before using sgb. > >>>>>>>> > >>>>>>>>> > >>>>>>>>> + bytestream2_seek(&sgb, string_offset + offset, > SEEK_SET); > >>>>>>>>> + while (bytestream2_get_bytes_left(&sgb) > 0) { > >>>>>>>>> + key[n] = bytestream2_get_byte(&sgb); > >>>>>>>>> + if (!key[n]) > >>>>>>>>> + break; > >>>>>>>>> + if (n >= sizeof(key) - 1) > >>>>>>>>> + break; > >>>>>>>>> + n++; > >>>>>>>>> + } > >>>>>>>>> + key[n] = '\0'; > >>>>>>>> > >>>>>>>> IMO this would be easier with strnlen(), avoiding sgb altogether. > >>>>>>>> You would of course need to explicitly check that you are not > >>>>>>>> overreading, but that is good practice anyway. > >>>>>>>> > >>>>>>>>> > >>>>>>>>> + chunk_start = avio_tell(pb); > >>>>>>>>> + avio_skip(pb, 1); > >>>>>>>>> + payload_offset = avio_r8(pb); > >>>>>>>>> + padding_size = avio_rb16(pb); > >>>>>>>>> + stream_index = avio_r8(pb); > >>>>>>>>> + avio_skip(pb, 2); > >>>>>>>>> + payload_type = avio_r8(pb); > >>>>>>>>> + frame_time = avio_rb32(pb); > >>>>>>>>> + frame_rate = avio_rb32(pb); > >>>>>>>>> + avio_skip(pb, 8); > >>>>>>>> > >>>>>>>> payload_offset and frame_time are set-but-unused; this might lead > to > >>>>>>>> compiler warnings. > >>>>>>>> > >>>>>>>>> + if (usm->ch[is_audio][stream_index].used == 1) { > >>>>>>>>> + uint32_t pkt_size = chunk_size - (avio_tell(pb) - > >>>>>>>> chunk_start); > >>>>>>>>> + > >>>>>>>> > >>>>>>>> This is unnecessary: Unless we already had a read error, pkt_size > is > >>>>>>>> chunk_size - (1 + 1 + 2 + 1 + 2 + 1 + 4 + 4 + 8). > >>>>>>>> > >>>>>>>> (Notice that in case padding_size is > 0, it will be part of the > >>>> packet > >>>>>>>> with the current code; not sure if that is an issue.) > >>>>>>>> > >>>>>>>>> > >>>>>>>>> + > >>>>>>>>> + avio_skip(pb, padding_size); > >>>>>>>>> + avio_skip(pb, chunk_size - (avio_tell(pb) - chunk_start)); > >>>>>>>>> + > >>>>>>>> > >>>>>>>> Simpler to just use avio_seek(pb, chunk_start + chunk_size, > >> SEEK_SET); > >>>>>>>> > >>>>>>> > >>>>>>> But input might not be seekable. > >>>>>>> > >>>>>> > >>>>>> And? You know that avio_skip(pb, offset) is just avio_seek(pb, > offset, > >>>>>> SEEK_CUR)? > >>>>>> > >>>>> > >>>>> And? Do you know that SEEK_SET is different from SEEK_CUR with > positive > >>>>> argument. > >>>>> > >>>> > >>>> You are using SEEK_CUR with -avio_tell(pb), which effectively makes it > >>>> an absolute seek. > >>>> > >>> > >>> Nope, I skip data only, not seeking backward ever. > >>> > >> > >> avio_seek() internally translates any avio_seek() with SEEK_CUR to an > >> absolute seek (as required by the seek callbacks) and does not care > >> about whether it is seeking forward or backward. > >> > > > > Irrelevant. Seeking needs enough cache to work on non-seekable input. > > > > Given that avio_skip() is just a wrapper around avio_seek(), the > behaviour will not change even when the input is non-seekable. > What you are trying to sell? That seeking works with unseekable input? > > - 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". > _______________________________________________ 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".