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. > > - 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".